Well that all sucks Rulzzz. Hope you are doing better soon I think the tea bag compress is how husband finally rid himself of his stye on the eye.
May not help a young person like you, but my joints have all felt much better with routine of lots of stretching, yoga, and light weight work. I walk, but never run on a hard surface due to previous sports injuries, so swim, exercise bike, or Nordic track for cardio. Don't do a lot of weight work on legs, but I think lunges are pretty helpful and may help the back too. Between back, knee, and ankle, stretching and light yoga may be a place to start to try and strengthen these areas, although there are probably some physiotherapy experts out there that might be able to give you better advice for preventative measures you can take with your injuries in mind.