Hello dear, Thanks for being on healthcaremagic.com. If you would have presented to me as an outpatient,I would have made the following clinical explanation- Though the symptom you have mentioned water in head does not appear to be classical for any headache type.However,looking towards the temporal profile of the headache it likely appears to be a primary headache only as it is episodic and episodes are infrequent(once in a 2 months).Most likely diagnosis,I can suggest here is Migraine .Migraine is an episodic headache disorder where headache is pulse like,unilateral(on one side) and is associated with the following typical symptoms are- 1)nausea 2)Photophobia and phonophobia(headache worsens on exposure to bright light and sound) 3)Visual aura Headache like water in head is though not typical but migraine headache can have bizarre presentations sometime.I would suggest you to visit your physician and discuss with him to put you on a trial of anti-migraine therapy.I hope it helps.