Getting over the flu or pregnant?

So I had protected sex on January 20 (about that day) and I am also on the pill. I had some that definitely seemed like my period for just 3 days but it was a little bit lighter than normal. I’m almost 90% sure there is no way that I’m pregnant but lately I had the flue maybe 2 weeks ago and now my body is tired and always achey and more chest has been hurting as well as my back. Two of my friends think I could be pregnant but one of my other friends and I don’t think its even a possibility due to the fact that we used a condom and I was on the pill. The condom didn’t break also. Anyone else have any thoughts?