head aches weight lose eye presure

my partner for about the past four weeks has been suffering for headaches for the first time in his life.He is 37 years old and one pupil is much larger than the other in the past few weeks he has lost around 7kg.
He has never suffered from head aches but lately even to have a shower and the water run on his head hurts.He has not suffered an injury his blood presure is fine and doesn't fell sick.
Please send me some idea of what could be wrong with him.

Get him checked immediately.

I saw one similar patient 2 weeks ago and he ended up having surgery for a haemorrhage in his brain. Any sudden changes to the pupil indicate damage or compression to the optic nerve or in the visual cortex within the brain.