“Unable to walk or bare weight on my legs”

Unfortunately your situation is too complex to be able to give you a good answer just from a few sentences of description. A thorough history and physical exam, as well as some imaging is probably going to be needed. My major concern for you, although it may not be the source of your problem directly, is that it sounds like you have a chronically infected total knee replacement if you have to be on lifelong suppressive antibiotics. Unless there is some major reason why they can't do it, typical treatment for that is to remove the implant, place an antibiotic cement spacer in your knee for 6 weeks while you are on IV antibiotics, then go back in and remove the spacer and put a new knee replacement in. It's a big deal yes, but so is having a chronically infected implant that can infect your bone... As far as your bilateral foot pain and left leg pain, if you say that you can't support yourself then i would make sure you get your lower back looked at to make sure that's not the source. Whenever something shows up

I assume your infection in your left Total Knee.I had a similar patient like you once and during a hospitalization wirer IV antibiotics weren't helping, I offered AKA, Above the knee amputation. Several days later after many talks with her daughter who was an RN, she reluctantly accepted. Within a few days she felt much better as the infection was ruining her overall health and the BKA removed all the infection. And she was thanking me.
Prosthetic technology has advanced so much that it is a good option if there is no Saving your leg. The Gun Smoke scene: Doc, Ya gotta save my leg no longer applies in every case.