Cramps and sore nipples :(

I need help guys. I am on a 30 day cycle. so yesterday was meant to be my ovulation I did an ovulation test this morning and it was negative. I did 3 tests a week ago and they came up with lines all of them. Today I woke up with really sore nipples. So sore to touch :( and I keep having pulling strange in my tummy. I don't know what's going on. Help anyone had this before. Also had a thick white discharge which was abit sticky come out before which am not too sure what it means