Recent nausea and vomiting after dives

Hey there, been diving for almost a decade now, 500+ dives under my belt. In the last 5-10 dives I've made I get a pounding headache part way through it, which absolutely ruins the experience for me. It feels to be in the very front of my head and just extremely "throbby". Once I get back to the surface I usually puke and feel better.

This hasn't really happened to me in the past and I would love to know what has changed that could cause this :s I don't have a cold, congestion, flu, ear infection; am not on any form of medication, nor am I dehydrated.

Looking for any advice or knowledge on the subject Cheers

tl;dr Get headaches after diving, want them to stop, not sick, help.