Unexplained Sneezing attacks

I have this strange allergic condition. After every 1 or 2 days, I get this sneezing attacks that lasts whole day. My eyes water, I get pain between my eyes and many times, there is stomach bloating too. There is no apparent reason behind it. No dietary reason or environmental reasons. I have it in every season throughout the year.

I have tried everything but this thing doesn't go away. I have to eat Cetrizine every time I get this allergy, which makes me sleepy and irritable. I don't know what's causing it. I have these attacks even when I am outside my city, so it can't be due to any particular thing in my house. It is the kind of problem that starts the minute I wake up and won't leave until I eat an anti-allergic pill.

I am fed up. Please help me.