Migraines?

I get exercise related migraines occasionally. I found that switching to barefoot running and focusing on smooth movements over jarring ones seemed to help. It may also just be your gym --- fluorescent lights? Extra noises? The air? There's a lot of environmental stuff going on at a gym that could contribute. Are you hydrated? What about other stress in your life?

Triggers tend to be additive. If it's just a cloudy day but I'm in a great mood, a migraine won't happen. If it's a cloudy day, I'm stressed, and I'm tired from the night before, a migraine is definitely going to happen.

As far as fixes go, maybe take a pain killer (2.5 Aleve is what I use, as per my doctor) as a "preventative" before you go to jog. It might help.

I struggle with migraines too, although have never gotten them from exercise directly. I do get them with visual triggers though and so there are places/things I avoid because I know they will result in a headache. Have you tracked what you did in the days leading up to the headaches? For example, certain foods, amounts of water, time of day, smells, etc? It might just be that there is another thing triggering them that the running is making worse and maybe if you can figure that out you could run happily. Also, have you had a physical exam with a doctor lately? If not maybe you should because they might be able to give you better advice about the migraines (or meds to help with it) or see if it's possibly related to another medical condition that could possibly be more serious that strenuous exercise could make worse. Curious to see what everyone else has to say.