Hi gang--real interesting discussion on all the theoretical possibilities of conflicting gas retention (BillP and DocV at a party-sheesh)
A couple of hypotheses:
Hyperventilation leading to CO2 retention seems likely.
Mask strap tightness probably not an issue--with the mask flooding and adjustments, the tightness of the strap probably didn't make a difference. Also, one might assume that the mask has been this tight before, without impact.
Final observation--check your mouthpiece. I'll bet you've got some great teeth marks in it. Under stress and anxiety, we sometimes have a tendency to clamp down and hold (don't wanna lose that mouthpiece!) This will cause a headache faster than anything else mentioned.
As you get more comfortable in the water, on a shallow dive, try completely relaxing your bite and let your closed mouth hold the reg in (it will). You won't believe the tension and anxiety that will go away.
Prolonged "kooky" feeling--your narcosis was gone probably by the time you cleared 50 feet. However, your statement of "feeling" the pressure leads me to believe that, with your mask problems and anxiety, you may not have cleared your ears often enough to keep the inner workings stress free (how's that for non-medical terms). If you let the pressure build too long, it can have post dive effects ranging from sore ears to tinnitus to dizziness and vomiting (although the latter probably indicates damage). Since it's cleared, I'm going to chalk it up to some hard clearing activity during the dive.
Equalize early and often; breath deeply and slowly, and relax your bite. Everything else will workout.
Disclaimer: This information is worth what you paid for it. It is opinion and personal belief. It's based on what you think happened to you so if anything is wrong, it's your fault. "Use or Don't Use--there is no 'Reliance", (Yoda, the untold story).
Cheers.
JR.
(Hi Bill and Doc-long time no chat)