Headaches/working out/Water intake questions.

[Austin]

I've been having bad headaches lately and feeling a bit dizzy/hard to focus. I recently started working out again after about a month break. One week I worked out 4 days, the next 2 (because I got sick), and then this week 4 days as well. This week especially my head in the front has been sore lately (hurts to move around, chew (crunchy/hard candy/food)... anything that makes my head vibrate/move). I'm wondering if this is attributed to working out, because I notice on occasion that my head hurts after working out especially bad. I'm wondering if I may not be drinking enough fluid. This brings me to my real question (unless anyone has any idea why I have these headaches and trouble concentrating)... When I drink water during my workouts, it makes me feel a bit uncomfortable. Like I feel a tad sick to my stomach when I drink and then work out. I've read lots of things saying to drink during workouts, but I don't understand how you can drink and not feel sick? Any ideas?