Ummm... HELP?! šŸ˜±

So I had unprotected sex about two weeks ago from today. I took plan b about two hours after this happened. This was also towards the end of my ovulation period. The next week I had a very light flow and felt bloated a good percentage of the time. That stopped after three days. Today my back and intestinal area are hurting like crazy. Not to mention my headache and dizziness. Is there a possibility I could be pregnant? If so, how do I tell him? He seemed so happy because I thought it was my period and I told him it was. He was so excited about it. We had a small pullout last night where I had him finish with a bj. He just seemed so happy to not have a baby. Now Iā€™m scared if I am, he might leave. Help!!!