headache when i bend down?

I have been vegetarian for almost a year now (it will be a year in april) and im not sure if that has anything to do with it. this headache has only lasted a few days now but
im afraid it might have something to do with not getting enough nutrients? to describe the headache, it only appears when i lay down or bend over. it feels like my head is going to explode (more than usual when i bend over) and i can feel it in my nose too and smell something weird. this could be a sinus type of infection but i read thats usually in the forehead region. my headache mostly occurs in the middle of my head, but a bit towards the back. what do you think this could be? does this sound like a typical nutrition deficiency headache? it could potentially be a dehydration thing also. i have been taking bladder infection medication recently. (im a mess lol).