Period symptoms

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So my calendar says I’m getting my period in 6 days. The last time I had unprotected sex was October 1 & I got my period after that I know there’s been cases where women still get there period even when pregnant. Even though that might not be the case you still get doubts you know. Anyway I’m just saying this because this time around my symptoms are rough my boobs hurt so much they are extremely tender & grew a size like even to the point where yesterday i had to ice my nipple because of how much it hurt. I constantly feel nauseous & maybe I’m just overthinking this but any advice on my symptoms