Slow-rising HCGs

[Katietwin]

I just found out I'm pg this past Sat. I'd had a cyst on my ovary, and became convinced it had ruptured, due to enormous pain on my left side, at 4am. The ER doc did testing, and made the announcement. I was shocked - we have been TTC for 4 mos., but if we'd conceived this cycle, I could not figure out how they'd pick it up already.

My HCG was 1212 that day. 2 days later, it went to 1768, and again 2 days after it only has gone to 2100. I'm also spotting red consistenly.

My Dr. will do an u/s today to see if anything is visible, but is really leaning toward thinking this is ectopic or otherwise a threatened m/c.

Can anyone advise how the heck my HCG could have gotten to 1212 for a first beta test in such a short time??? Also, if this is to be a m/c, how long can this take to work itself out? I would rather know, and just get past it if this is what's in the cards. It's too hard being in limbo, if that makes any sense.