you have ´headaches´ at the base of your skull while pushing heavy weight and yellling....
Is it more of a cramping burning sensation at the occipital ridge of you skull? sounds like a combo of the weight of the bar on your shoulders... and how you might be protuding your chin (hyper extending) your cervical vertebra... your neck while trying to project your voice to teach. As you are squatting, if your chest dips and you are ´reaching´ with your neck as you instruct class, this would definitely fatigue the muscle attachments around the base of your skull and cause pain and possibly headache.. Everyone here has made some good suggestions.. drop back on your weight a little, keep hydrated, see your chiro/doc if it persists... as importantly keep your spine and neck neutral as you squat, from the base of your spine to the crown of your head. Get yourself a microphone so you dont have to yell so much while instructing... I know in BodyPump the loud vocals keeps up the motivation... but for your own safety, keep your eyes straight ahead and focus on your own form a little more as you teach.
Good Luck... and get a nice professional neck massage too!. Kathx
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