My 18 month old son has now had three "episodes", the first one occurring five weeks ago. An "episode" always occurs a couple of hours after he goes to bed for the night. I can here him moving through his monitor and then a few seconds later he starts crying like he has just had the worst nightmare ever. For the next five to twenty minutes (twenty being the longest) he doesn't have any real control over his limbs. I have to pick him up because he hurts himself trying to get up and falling on his face. He does not have solid movements they are weak and jerky. As I said he cannot support any weight, including sitting up or holding his bottle. When he tries to hold his bottle his arm jerks back and forth causing him to drop it. I took him to the ER after the first incident and the doctor told me it sounded mysterious, but my son seemed to be fine now and I could go home. Is there something wrong with my son, what could it be, and how serious is it?