Repeat chemical

One sept 8th, I had a chemical pregnancy at 4 weeks. Sometime right after I got pregnant again. Numbers looked good and doubled. Got started on progesterone. Yesterday I had some back pain and my heart sunk. Sure enough took a pregnancy test and it was negative. Went to the ER, hcg dropped to 4. So another chemical. Going to the doctor tomorrow to try to figure out what’s going on. Anyone else have any back to back and ever found out why?

Idk if I can keep trying with this heart break 😞