Overthinking?

What kind of discharge would I have if I am supposed to start my period today, but am also worried that I may be pregnant. I had sex 3 times this month with a condom, and tried unprotected sex for a few seconds, but realized it was a bad decision, that's why it was only a few seconds. He urn instead before so I'm sure there wasn't a chance of pre cum. 1 day ago I had back pain, which I usually do while on my period if not right before.. Other than that I feel pretty normal, I am also on a very hardworking dance team, I exercise for that 5 times a week for 2 hours, I am not sure if any stress or exercise wouldn't affect anything? Please help me clear my mind from this! I am worried yet not at the same time! A few responses would be helpful:)