Unusual headaches lately

So 3 or 4 workouts now over the last month I have had an horrible headache in the middle of the workout. I don't have a headache before I begin and I have been able to get through a warm up pretty well.

It is a sudden onset, on the left side, backish area of my head and it feels like it is filling up with pressure and then just pounds uncontrollably. Last night I warmed up 10 minutes on the ARC trainer, stretched out, did some jumping jacks, box jumps, and push ups to get my muscles open and I was all good. Then, I began my workout. I did 21 front squats, 21 pullups, and I started 21 burpees. At about #8.. I couldn't go on.

The last time I remember this happening I was doing side to side jumps. Yesterday I stopped, sat down for a few minutes, got some water and my head was still pounding. I didn't get to finish the class and I continued to have a headache the rest of the night.

I will say that I have had a history of tension and migraine headaches but this was different. those I control with chiropractic visits and an anti seizure medication I have been taking for nearly a year.

Anyone else ever experience these kind of headaches? Any thoughts or advice on preventing them or what could be the cause?