My 6 yr old mid spectrum son has always enjoyed swimming and being taken to the swimming pool, he seems to enjoy getting lost in the noise and thrashing at the water. However when we took him yesterday he seemed to have developed a tic whereby he has to push his face into the water briefly and then back out again. Now he doesn't enjoy doing this and finds it quite distressing and says that "his head is thirsty" however he doesn't need a drink. In addition we've noticed he does this in the bath (different environment, no people, no noise) and doesn't like taking a bath now, much preferring (and really enjoying) taking a shower. The depth of the water seems to have some effect but he'll do it even in a few inches of water in the bath.
Does anyone have any ideas what's going on in his head at all as we're stumped and want to try and make sure he can go swimming when he wants to without the distress?