Yesterday I was 13 dpo took a test in the morning and it was a bfn. Later in the afternoon I started spotting and got cramps. By 8pm I was having more of a flow and worse cramps. When I woke up there wasn't much on my pad which is abnormal and now I'm having pretty bad cramps and the only time I really bleed it when I'm on the toilet (thick and dark and drops to the bottom) usually I bleed heavily and change pads often. This is my second "period" off the pill. Is this just my body getting used to a non pill period?