How can i build up my strength?

Buy one of those large exercise balls that you can sit on. There are plenty of exercises you can do to strengthen your core muscles and pretty much every muscle while keeping your arms free. I would go to a physical therapist first to make sure you are doing the exercises correctly but a video should do fine. Also walking and water aerobics with only leg weights should be good for you. Best of luck!

You need to do it slowly, with a one pound weight exercise. The doc. or therapist will tell you witch to do. You can hurt yourself if you do too much to quickly or the wrong exercise. So, I don't think we should advise you, unless we are doctors. I hope you feel better.