Spotting for 10 days!😣

Hey ladies. According to my lmp I should be 7 +3 today. Went for an ultrasound last Friday and all they could see was a tiny 4-5 week empty sac. I know my dates can be off since I wasn't tracking ovulation. My worry is because for the last 10 days I've had this very very light spotting ranging in color from brown to orange red to tan to red. Most of the time it's not even enough to show when I wipe but only when I check internally. Last night, however, (several hours after orgasm with no penetration (sorry TMI)) I had a light flow of very bright red fresh blood. Only lasted about 10 minutes and was about the size of a quarter on a pad. No cramps nothing. I was actually surprised as I had been cramping pretty mildly but regularly for weeks. But no pain what so ever associated with the little bleed. This morning it has gone back to a very light brown spotting only internally again. I don't have my follow up appointment for another 10 days so I'm hoping for some stories of encouragement. Anyone ever heard of anything like this before? Good or bad. This is my 4th pregnancy and I've never had any complications whatsoever with my 3 boys. Trying to stay calm but this waiting in so nerve racking!