bed wetter 14

My son has been wetting his bed for 14 years now. On occassion he has dry spells that last a week or two, then he could be wet every night the next month. We have tried body alarms, reducing intake of fluids, even waking him up in the middle of the night. Sometimes he will be wet at 3 am and again at 7:30 am. I don't know if the following symptoms mean anything, but here it goes: he sleeps in the fetal position, the light going on in his room bothers him, he sleeps deeply (impossible to wake him up), he has bad exzema on his arms and leg, terrible seasonal allergies, and for what it's worth, at birth he had his umbilical cord wrapped around his neck and did pass stool. I am open to anything. My son is truely exhausted of this. Please help us, thank you.