Delayed headaches

When Rex takes control afterwards I get headaches but they can be quite delayed, why is this?
And is my curiosity of what he's been doing getting the better of me.

Well, the body's pretty complicated and there's a lot of physiological reasons why you get a headache. You both share a body and even if he's not the one one out you could be feeling his headache.

That's how it happened to me. When Jake was almost 17 he went to sleep one night and I woke up the next morning with no clue of what had happened to my personality. He was going through a lot back then and simply didn't want to exist.

Jef