My last menstrual cycle was 10/22 its now 11/26 my cycle is usually 28 days long. Yesterday 11/25 i noticed brown discharge, looks like old blood at the end of a period. I put a pad on thinking my period would start. This morning i wake up and theres nothing on the pad but when i wipe, the same brown blood is on the toiletpaper. My breast are sore, i dont know what else to do, ive taken 4 pregnancy test (afternoon) they came up negative.