Agree with all. And by coincidence I have been thinking of Stephen Hawking this week, too.
I still have back problems left over from caring for my golden retriever 10 years ago. Your post reminded me of what it was like at the time, always going around in a haze of pain and discomfort and trying to ignore it. I hope you are taking something for your back. Medicine doesn't cure the strain but it might take the edge off. I do not find Tylenol does much for my back, but Aleve does. Different medicines work for different people I guess. In fact a doctor once told me some people respond better to Advil and some respond to Tylenol, apparently our systems differ. I like Aleve better than either of those, but when I cracked a rib Aleve didn't work and Tylenol did. If you tried a pain reliever that didn't help much, I would really encourage you to try another one and maybe it will. I ended up going to physical therapy after my dog passed because I never blew a disk but I managed to mess up my back in a lot of other complicated ways from the cumulative stress and strain of 8 months of lifting. It's real.
A dog carries 60% of his weight on the front legs and 40% on the hind legs. A 90-lb dog carries about 36 lbs on the hind legs, so you are lifting 36 lbs when you help her stand. But if you lift the hindquarters so the dog is on his feet and he then immediately starts to walk somewhere, that is a little extra pull on you, so you are supporting the 36 lbs plus the pull which would essentially translate into a few more pounds. I don't know how to calculate that. And you depend on the dog to be able to rise on his front legs by his own power when you lift the rear.
There are several ideas that might be tried for lifting. You may be a little beyond wanting to try such things, but I will post the links just in case.
There is something called a Doggie Lift. It has been out since at least 2016 but I only learned about it recently. I wish I had had it back in 2009 when I was caring for my down golden retriever. I have not tried the Doggie Lift and do not know if there are any issues. It is designed to work in a doorway with a traditional frame around the door. The main issue I see with it is that you need to have your dog in the doorway to use it. Here is the link.
viewtopic.php?f=22&t=21554
If you happen to be someone who owns a shop lift, it can be converted to a dog lift. I did that for my golden retriever. It can be a little inconvenient to have to use it every time, but it does save you having to lift the dog yourself. I never would have got my dog into a 4-wheel cart without it. I found it was especially helpful to get Merlin in his 2-wheel wheelchair, because I needed him to be on his feet and I needed him to stand still. By hooking his harness with the lift, it kept him standing in one place while I got him in the wheelchair.
http://www.handicappedpets.com/mediawiki/index.php?title=Engine_hoist_for_a_heavy_dog
This is another idea. By the time I tried it, it was almost too late as my back was already shot. I wish I had thought of it sooner. I found that I could use a tall wrought iron plant holder from Home Depot. I could hook his rear harness and anchor the base of the thing firmly in the carpet and brace it with my foot, and it allowed me to pull him to his feet in a different way than I had been doing. I do not know the physics of it, but it was easier to do than a normal suitcase lift. I will attach a stick figure drawing so you can see it. It did actually work. Once he was up, I had to drop the pole and then I still had to support him myself...but he was up! It was only for getting the dog up from lying down. I don't think it will work on a slippery floor. You need carpet to anchor it. In the picture, I drew it showing 2 hands on the pole. You can do it with 1 hand, which allows you to turn
sideways and pull one-handed, putting less strain on your back.
viewtopic.php?f=22&t=12985
There was another way I found to try to lift him, which also worked well if I was careful.
https://handicappedpet.net/helppets/viewtopic.php?f=21&t=12503&p=64959#p64959 wrote:I have an upper back problem, which is different than usual--most people have lower back problems. I have found that one way I can get my dog up without straining myself is to half kneel, with one knee on the floor and the other bent. I rest my forearm on the bent knee (which serves as a table) and lift the dog by grabbing the rear harness he is wearing and doing a curl with my biceps. My elbow never leaves my knee, and I do not use my back at all.
Here was the drawing (not great but it gives the idea):
viewtopic.php?f=22&t=15423&p=82235#p82235
Here is a post describing
what went wrong with this lifting method one time when I overextended.
viewtopic.php?f=30&t=12959
And here is a pulley system someone used with a rottweiler. It isn't a common hardware store pulley, they used a marine winch designed to lift boats out of the water.
viewtopic.php?f=66&t=21785
I have several pets, so when I lose one, it leaves a hole in my heart and life, but I do still have others. Some people go right out within a couple of weeks and get another one. Other people wait. Sooner or later you will probably find yourself looking at websites like Petfinder or the animal shelter or breed rescues where you might find a dog. Just because you are looking doesn't mean you have to adopt one right away, you can just look.
I don't think I've ever had 2 pets that reminded me of each other in their personality. They are very different, even if they are the same breed.