Bulging discs

My husband fell on his back pretty badly few months ago. He has been better and worse, now his legs started to go numb, so he had CatScan done which revealed he has few bulging discs in his lower back.
His doctor told him that therapy might help. Now I was wondering how serius are bulging discs, and what kind of exercise he should do and what he shouldn't. He lifts weights, and I am not sure he should continue. Any ideas? Also any ideas on any supplements he should be taking???