I think others may have mentioned it, but I would say mask strap as a possible issue, or constriction of your eyes (squeeze) due to not equalizing your mask might be another one. Pressure on your eyes can cause intense headaches after a while.
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
One question not asked or answered yet: Do you smoke?
I had a student a while back who surfaced with bad headaches especially in higher altitudes. Through talking to him and consulting dive-MDs, we deduced that his chain smoking combined with being overweight and out of shape was causing CO2 Retention Headaches!
"consider your lungs exhaust air like a car exhaust"
Except that the exhaust that comes from the car, or a badly filtered air compressor, is CO, carbon monoxide, and our lungs exhaust CO2, carbon dioxide.
If I'm doing multiple dives I use a camelback strapped to my tank. Keeps me hydrated and avoids cottonmouth. Wait on that until you have some more dives, though. You don't want to get task overload.
Are you drinking plenty of water and staying well hydrated before the dive?
Probably dehydration. People just either don't understand or neglect to understand how dehydrating diving is, especially in salt water.
If it were CO2 retention then the headache would have been very sharp but not lingering.
Thanks for all the answers so far.
#1- I have had some jaw problems but after replacing my mouthpiece that has gone away.
#2- The tanks always get filled from the same place. I will look into buying a C02 gauge.
Unlikely, but who am i to say don't
#3- I will try and drink more water before my diving. Maybe its not enough?
If you don't pee in your suit or come out with an urgent need you are probably running dry.
#4- Feels like I breath OK but will try and breath even deeper and exhale more.
Exhale is the key. The rest will happen.
Do you wear glasses? Going uncorrected for a spell can take a toll.
Pete