TMI discharge possible miscarriage?

Kind of gross but this afternoon I had a pretty large chunk of clear mucus discharge (about the size of a fingernail) that was round and hard. There was a tiiiiiny speck of possibly blood that looked like a flake of pepper in the center. I am 8 weeks tomorrow, had an ultrasound at 6 weeks that was normal, but now I'm freaking out that that could have been a miscarriage or sign of one? I have had no cramps at all and absolutely no bleeding, and previously just normal discharge/CM. I know that if it was a miscarriage the baby/sac at 8 weeks would be much larger than that... Has anyone experienced this and found it to be normal? Or found that it was a miscarriage? Should I call my doctor or am I freaking out for no reason? I have an ultrasound on Thursday and I really don't have any time to get in before then anyways, but now I'm so worried, was planning on telling our parents this weekend :(