It sounds like its just old blood probably with some cervical mucous. I had a fairly severe SCH with dd1 off and on about half a dozen times all through pregnancy. As you can see from my sig she was early (33wk 6ds) because of a late bleed but she was perfectly healthy just tiny! Try not to stress and do rest up as much as possible, evidence suggests there actually ISN'T anything that can be done but overdoing it will possibly worsen things. Other than that make sure you're getting plenty of zinc and vit C which is essential for vein making and healing. All the best!