Swimming may or may not help--im a swimmer and I've injured my back dead lifting
I just injured my back on thursday and today im walking like normal. But in your situation I know what you mean--fucking feels like a white hot knife in your back *yikes* lmao
when shit like that goes wrong the nerves/muscles arent firing in your back properly and they have to be reactivated.
unless you have an actual athletic trainer go to the doctor or a back specialist. In all my instances of back spasms its been caused by my hips/pelvis being out of alignment. how it can get realigned is difficult to describe and I wouldnt suggest doing it yourself because i dont know what the risk could be.
After realignment some exercises that can help rehab it are:
1) lay on your back with your legs straight out. next lift one leg up in the "L" shape like youre about to do crunches. wrap both your hands underneath the knee point. pull on the joint with your arms while trying to pull your leg against the arm force--you should feel it in your back. do it for about 10 seconds then switch legs
2) lay on your back with your legs straight out. next lift one leg up in the "L" shape like youre about to do crunches. this time put both your hands on the part when the thigh meets the knee cap. push against your thigh while using your leg to push against your hands--you should feel it in your back. do it for about 10 seconds then switch legs
3)this is a 3 series exercise all done on your side. lay on your side with your legs straight. Lift the top leg up and back down 10 times and then switch to the other side. keep your ankles together and bend your knees so that your ankles are beneath your butt and in line with your laying body (they should not be touching your butt). lift the top knee into the air and back down while keeping your feet in contact with each other for 10 reps then change to the other side. Lastly move your legs into the "L" shape while still on your side. Your body should be like youre sitting in a chair. move the whole leg together up and down for 10 reps--flip to the other side.
4) childs pose (yea the yoga move)
do it exactly as shown then sit back into the pose and lean into the back left leg/side to get the stretch on the left side of the back and vice-versa for the right side.
5)get some "stim" done with a hot pack on top of it. stim is short hand for "stimulation" and its pretty much electro therapy on the muscle tissue to get the muscles firing (read: contracting) again and the heat helps loosen things up back there.
http://www.youtube.com/watch?v=oZ7LlfBlZF4
heres a more fun video where you can see the muscles firing lmao
http://www.youtube.com/watch?v=eW4OkFvua_s
hope this helps brotha