If it's a miscarriage and you were far enough along for a pregnancy test to detect it, a test could detect the hormones still in your system for a brief time after a miscarriage.
Hi there and welcome. Well, if you were late or had unprotected sex, then sure, it could be a chemical miscarriage which means a very early miscarriage--- almost to early to say you were really pregnant. It could be a simple cyst passing as well which does cause increased cramping, heavier bleeding than normal and some clots. I would see how things go after it is over but women do have issues like this from time to time. Are you trying to get pregnant? Had you taken a pregnancy test or anything? good luck