Tender uterus

Be
Hey lovelies
I'm writing this because for the last week I've been neauseous and had a tender, full feeling in my uterus, even aches to sit down... With lots of ewcm
I'm still breastfeeding my little man, and have regular cycles and am due for my period any day. I don't know what I'm really asking, but is this normal? I took a pregnancy test this morning which was negative. 
Thanks for taking the time to read lol xx