Sorry to hear that, it is nerve-racking to not know the reason. Everyone’s case is different, and nobody can tell you for sure what it is or is not without a proper investigation. I had severe headaches for years misdiagnosed as migraine before finally putting my foot down on a scan which found a small low grade tumour. It was not what was causing the headache and other symptoms though - the bigger problem was that it had gradually grown to block CSF flow, so my ventricles became massively dilated pressing on the surrounding brain tissue. I was lucky to be alive and not paralysed or blind. Chances are, you have no tumour, as it is quite rare. Trouble is, any small irregularity in the brain (or another system affecting the brain) can cause massive and often irreversible damage. Not just physiologically, but mentally, emotionally, cognitively, with resulting effect on quality of life. Better check and catch it early. Better safe than sorry. Good luck.