I can't even stand up straight

I can't even stand up straight--my musculo-skeletal system is so messed up. My knees can't stand any weight on them--they are messed up as part of the overall problem. Last night I learned about knee pain, as I had shooting pains going thru my knees. Now my body knows--DON"T WALK and DON'T STAND UP STRAIGHT. To be honest, all i want to do is crawl on all fours, but I keep trying to walk. Can't feel my lower legs at all. I keep looking for work but don't know how i am capable of working when i cant even walk.