VERY sore breasts !!!!!

Janice • I`m 29, husband is 31. I have pcos and a bicornuate uterus. This is year 3 ttc. MC in y1 Baby #3 is now 16w 2d`s
I had a very light brown discharge on and of for a week, 5 weeks ago about a week after I started having very sore breasts and nipples and have had them now for 4ish weeks. I took a hpt 2 weeks ago and was negative. Any suggestions anyone as what it could be??? Did I test to early or maybe a hormone charge but isn't it a bit long 4 weeks??