Pink discharge

Hi everyone, please can someone help or give me advice. Me and my partner had an insemination on 15.11.15 (3weeks today) my period was due 7days ago and didn't show up. We did a pregnancy test which came back negative. And today randomly I got a pain in my stomach and had pink discharge with pink blood. Thought nothing more but as the evening has gone on its got heavier, and a few clots. Can anyone who has experienced this or no what it may be give me advice please? Thank you for taking you're time to read this.