It looks like a clump of boogers. You are probably gradually loosing yours but since they can regenerate its not really something to worry about unless it has blood in it. I lost mine repeatedly from 22 weeks on and then at 38 weeks I lost one that was mixed with blood (bloody show) and had my daughter 36 hours later.
iv found having unprotected sex does the same thing to me, iv been on the phone to midwives from 14 weeks and they say unless its accompanied by cramps/ back pain or is pink or blood stained you should not worry too much. it does regenerate but i know too well the shock of finding it so early on lol best of luck xo