Bleeding and cramps. Anyone else?

I've been having some bleeding and cramps today (no recent sex to blame it on). Really making me nervous. Have my first ultrasound this coming Tuesday, which should tell me if things are on the right track or headed to a miscarriage, but that seems like a really long time to wait right now. Anyone else having now or maybe had symptoms like these in a previous pregnancy? This is my first, and I'm very anxious about what it means.