Answers please!

My bf and I have been trying to have a baby for 6 months. It would be our 3rd. About an hour ago, I had a sharp/cramp feeling in my pelvic area on the right side! I have been told two different things and would like other opinions! My period was from the 8-14 and I had sex 18-21 and then this happened. What could it be? I need answers before I spend money on a pregnancy test, or go to the doctor. I have been really tired, moody, acne, and having head aches!