thought period started but then went right away.. HELP!

so ladies. I had intercourse the other night and yesterday morning I got what I thought was my period so I got up put a pad on and went back to sleep. I woke up again and checked and there was no more blood only streaks of red in clear CM. my cycles are irregular but I'm on CD 36 right now. I took a hpt and it was a BFN. I ended up calling my doctor and leaving a message cause I don't know what's happening. has this happened to anyone before??