Last chance

Yeah, it sounds like a typical state of sarcopenia where just lifting objects, climbing stairs or just getting up from the couch as well as balance issues and the main symptoms of basically having a frail and under nourished metabolism, where the legs are basically holding up your world and failing miserably. Legs are the key component and need the most focus imo.

I suggest that you contact or look into any gov't agency like the National Institute on Aging (NIA) or Foundation for the National Institutes of Health (FNIH) or what might be available in your Country, which I believe might be Britain or you can contact a gym and ask if they have any programs that deal with older adults and ask about sarcopenia but suspect that would be a high priority if they have a program, most do.

The important thing in my opinion is you begin this recovery phase by slowly and with a dedicated progressive initiative where you record your progress to begin to move and by that I mean just move more than you are now. For example that could be just doing "sit to stand" exercises and yes you can start with doing one. if you need support doing that by using your arms then the first goal would be to do that without, do you see where I'm going with this. "wall pushups" where you stand a few feet away put your hands on the wall shoulder height, lean forward and push yourself away, and yes you can start with one. If you research exercises with sarcopenia you will be well supplied with examples you can use.

Nutrition and diet play a key role in this endeavor and shouldn't be underestimated. I suggest a focus on quality protein be a key component and by quality I mean animal protein, this I can't express enough, and suggest you consume about double your RDA recommendation, and no that's not too much, it's been recommended to low and that's been confirmed by every clinician and scientist that studies this subject. I also suggest that most of your food come from whole foods which will by default increase satiety and facilitate a metabolic status within the body to better deal with hormonal issues that can create signaling that supports that satiety and cravings generally tank lowering the possibility of bingeing.

I do suggest that you get your blood panel updated and talk to your PCP and tell them what your plan is. Certain nutrients are also important and you can also talk to your PCP about this but the familiar ones that we don't want to neglect are VitD, that's a big one, calcium, magnesium, zinc, B12, omega 3's, vit C and iron and again talk to your PCP and hopefully they know at least the basics and can inform and direct properly.

Old and unable to walk is preventable, just start now and put a plan together and as Yoda would say

"Do or do not. There is no try."

This may not be your issue, but it more common and just though it might help you or possibly other people reading this, cheers! and good luck with your mission.