Caught your eye, didn't i?

this question concerns my boyfriend and his masturbation "problem". Frankly, i'm at the end of my tether on this and so i'm looking for anything that will point me in the right direction.

His problem is that he gets migraines, like clockwork, 2 days after masturbating.

But here's the thing; if he's having sexual relations (actual intercourse or me masturbating him) with me, he does not have these problems. Only when he is masturbating himself. Only solo does he get migraines.

I found out about this because of his insistance to stop masturbating altogether (with varying amounts of success). Without having any religious convictions (he was raised agnostic) or any specific phobias (no feelings of guilt, sin, or wrongness...Or fears of making messes), he has decided to quit completely. He says that he had no migraines in the month that he managed it, and only gets them after masturbating.

My question is twofold, so here it is:

has anyone heard of this before, and/or does anyone have any theories or suppositions about what this might be? If I get ideas for questions to ask him, I bounce them off of him. Any thoughts whatsoever would be appreciated...

And 2) should I just, you know, drop the issue? I mean, it's not as if he needs "permission from [his] girlfriend to masturbate or not" (his words). But it's not the do or don't, it's the reason behind it that concerns me. The choice itself is fine. The grounds on which it is done need some looking into.

Your thoughts, please?