What Causes Headache After Nightfall?

sir im a 22 year male i have a problem when i m having a nightfall next two or three days i hav so much headache i had treatment with various neurologists and i also had ct scan and mri of head but they didnot get my headache problem i think i didnot tell them truth of my headache
size of my pennis in standing position is 3 to 4 inch & i didnot hav spurms
pls sir give me an advise
can i transplant it sir pls guide me