Help!

Hi! How is everyone? I know I haven't been on here in a while. I just really need to find out what I can do to get back to losing weight. I had gastric bypass done in May 2008. I started out at 309 and right now I am at 235. I seem to lose a few pounds and then hit a stall. Then I will gain and back and forth. I have been going to the track about 3 times a week walking anywhere from 2-4 miles each time. Well, back in Nov. I started having major back pain and coming to find out I had a bulging disc for the 2nd time since May of last year. It gets to the point where my right leg is constantly tingling because the bulge is on the main nerve and so my surgeon is wanting to do surgery but telling me that it will fix my leg but can cause more pain in my back. I started back walking today and by the time I walked my 2 miles I had no feeling in my right leg at all. I am scared that if i keep walking it is just going to hurt my back more. I have got to some how get back to losing my weight. I want to get under 200 so bad. Any advice would be very very helpful in the situation I am in. Anything you could tell me I would appreciate it a lot.

Thanks
Sonya