Thank you everybody for advising. On a second though I agree that CO2 retention may be the culprit. Cold water increases CO2 production and being less fit now I spend more energy and produce more CO2 for the same exertion and water temp. Though I am quite an experienced diver/swimmer, and a hood seems to be alleviating the problem... Had anybody had headache from (cold) water getting into external ear canal?
I will also try paying more attention to breathing patterns and maybe try hyperventilation after the swim, see if it helps.
I will also try paying more attention to breathing patterns and maybe try hyperventilation after the swim, see if it helps.
