Headaches That Come And Go Like Clockwork?

Say folks, got a rather strange (for me anyhow) headache problem here.

For the past couple of weeks i've been getting headaches that start at around 8 am and last until around 11. They always start to taper off at 11 and then they're gone for the rest of the day.

This hasn't been every day, but it's been frequent enough that i'm a little concerned. They started a week ago last friday, then stuck around on saturday and sunday. Then I was fine all last week, but this past saturday and sunday, the headaches came back. Then I was fine yesterday, then the headache was back this morning.

The pain is not unbearable, but it's pretty dang bad when it comes. My mom (she's a nurse) thinks it might be allergies or sinuses and I think that sounds right, because when the headaches come, my right eye waters (the pain is mostly on the right side of my head) and I begin sniffling, etc. But of course by 11, the pain is totally gone and my eye is dry and I have no more sniffling, etc. I've never heard of headaches that are quite so clockwise, but that seems to be my situation.

I've started taking (over the counter) allergy medication, I believe it's made by tylenonol. That helps a little, though not too much. I've also started drinking more water, because some folks have surmised that I don't drink enough (and they're right). That also seems to help a little, but sadly it hasn't solved the problem entirely.

I was wondering if anyone has had a similar experience, or has any thoughts on this, how to best remedy it, etc? Rest assured any and all input would be greatly appreciated. Like I say this pain is bearable, but what the hey, if there's a way to decrease it- I figure it's worth investigating.

Thanks so much in advance for any input anyone can provide.

Cheers,

snaithbert