Here's the latest:
Everything has now been ruled out (stroke, MS, any central nervous problems, tumors, lyme disease, any heart defects or infections). The doctors feel this is something viral that will have to run its course and we need to focus on rehab to build his strength back up and retrain his brain to move his left side.

He is actually going to be discharged today, either going to an in-patient rehab facility or home to do intensive PT. We are waiting for the rehab doctor to examine him to determine where he is going.

Yesterday and today he is actually showing small signs of improvement. He is now able to lift his left arm a little higher and when he squeezes with his left hand you can actually feel a little squeeze. Yesterday he was able to walk down the hall to the special shower (it has a bench) they have with assistance, limping all the way. Once we got there he was too exhausted to do much more then sit on the bench and hold the shower head while scrubbed him down. He then needed a wheelchair to get back to his room. As the day went on he went on three more "walks" to try to build up his strength - each walk was no more than two minutes, but it's a start. I'm a little concerned about them sending him home since we just have the one bathroom UPSTAIRS, but I'm going to get dressed so I can head back to the hospital with the kids so they can see Daddy but also so I can be there when the rehab doctor is there so I can voice my concerns.

Thank you all for the amazing support you have shown me through comments and offers of help. It has helped so much to know that so much is taken care of.