Why do I get really bad allergies in the Night?

This never happens in the day but only in the Night. It seems almost like if I have the flu... but i Don't. Every night for like the last month, I've been starting to get really bad allergies in the Night. So bad, I need to have the tissue box right next to me. I sneeze like ten times at once and have a really stuffy, runny nose with a little congestion. I'm a 16 year old male. There is a fan in my room, but i don't think that's it. There are no pets in my room, besides a hamster and a fish, and this has never really happened before. Today I woke up at 2:00AM because i couldn't go back to sleep, cause of the allergies. My bad sheets are really clean. What is this? Is there any medicine I should take? I really don't want to go to my Pediatrician, Should I? Please Help.