That would be horrible if they gave you the methotrexate and the baby was actually in your uterus.
I hope they're following you closely with both bloodwork and ultrasound. I didn't have the sharp pain on one side like you read about are typical with ectopics. Instead I had very uncomfortable gas pressure-like pain and two 30 minute incidents on consecutive days of bright red bleeding. Ectopic was suspected but ruled out during my two ultrasounds that second day. I had something sac-like in my uterus (pseudo sac likely) so I first had a D&C but no embryonic tissue was found (and I hadn't passed any during my bleeding incidents) so I had another beta and it had risen despite the D&C so I had a laparoscopy where it was confirmed to be ectopic. At 6 weeks 4 days, my HCG was 6000.
Methotrexate becomes less effective the higher the HCG rises and apparently it isn't unusual for it to rise during the first few days after the shot.
Either way, it's a devastating situation. I hope you get answers soon and my thoughts are with you!
35 years old - SMBC * 3 ICIs, 6 IUIs, 1 ectopic, 1 chemical, blocked left tube.
Lucky #10 - IVF!
Two sweet baby girls (IVF 2015, FET 2017)