Spotting 3 DPO

Just curious I am in my 4 ttc cycle. On Sunday my husband and I BD and after I had very light pink discharge that stopped after an hour. Come Monday night I then started to spot brown and still am at 3 DPO. I know for sure I ovulated on Sunday per my positive OKP test on Saturday and then temp dropped Sunday and the last two mornings temp has spiked. AF is not due until the 19th, but I'm freaking out about this spotting! Has anyone else experienced this or have any advice?