Possible miscarriage?

This is my fourth pregnancy. I have two little girls and the. I miscarried in May at 16w. Now I should be 5w5d and tonight I had really intense cramping that lasted only about 5 mins or so. I started bleeding and it was bright red, there was one clot about the size of a quarter. Now I am just spotting a little bit and it is more brown than red (so old blood). Do you think I should be ok or should I continue to worry? I am supposed to have my first appt wed morning.