I have severe headaches, back of head, lower right side. sometimes after too much alcohol, sometimes no trigger? the pain can last for days. help.

Needs investigation : You need to check with your pcp, who should check your medical history, family history and any risk factors. You will possibly need ct or MRI brain to rule out any organic pathology. You also may have some withdrawal headache from the alcohol, or tension headache. It's important to know what alleviates the headache and what makes it worse as well. Hope you feel better.