I've Been Having Infrequent Dizzy Spells Lasting A Max Of

I've been having infrequent dizzy spells lasting a max of 10 seconds for a few years, which I've put down to hormone fluctuations as I'm 47....recently the back of my head felt hot inside...like it was sunburnt, I'd been on holiday snorkelling so put it down to that...last night I had another dizzy spell when I stepped out of my car and this morning I've woken with a sore hard lump on the top left hand side of my head.
My boyfriend complains I have a terrible short term memory...