Hello doc I had spotting thread like once in a day on 7,8&9 dpo then it stopped and again from 13dpo i am having brown discharge today on 15 dpo i am having little more discharge. I am also suffering from mild to moderate backpain from 4dpo and today i had light cramps on and off. My period is late by 4 days took pregnancy test at 12dpo but its negative. What may be the reason for this symptoms and on and off spotting???