Sore breasts while exclusively pumping

I'm exclusively pumping my newborn. Im pumping probably around 10x a day (even at night). My boobs are SO sore, like it feels like im about to start my period. Is this normal? I honestly am kind of just pumping whenever baby eats, not on any schedule or anything and I don't know if im pumping long enough. I don't know what im doing basically lol 😳🙃 any insight?