Cramps, pulling, and sore nipples?

I had my period at the end of July. It wasn’t really normal but it was bleeding and I took it as my period. Since it ended, I have been nauseous, it’s feeling like my ligaments in the lower belly area are pulling and cramping and my nipples are sore. I know that some women find out their pregnant after they had what they thought was a period but I don’t want to think it. Yes I was sexually active the month of July but I honestly don’t feel comfortable going to a big store to buy a pregnancy test. If any one has had something like this and it was pregnancy or was something else, please let me know. I don’t want to give myself anxiety going to the store for a test when it’s just hormones gone wild or something else that know would have thought of. Thank you again for you input.