I had unprotected sex on the 2nd, 3rd, 6th, and 7th of this month. He came in me all 4 times. I had my last period on September 24 and shouldn't be due for my next one until October 22. I just recently today started feeling really nauseous, bad headache, and so tired. Pretty much slept all day. Is there a chance I could be pregnant? And if so when is the soonest I can find out?

Of course there is a chance, since you had sex, even if you had used protection, there is a chance, since no birth control is 100 percent.

Now it is merely a waiting game, you will have to wait till it is time for your next period and see if you have it or miss it. After you know you have missed it ( if you do) then you test.