Faint lines for days - upper abdominal pain

I had a bfp 3 days ago. It was a pretty late bfp at 14 dpo (confirmed with opks and temping). That was my first concern as I have read later implantation has a much higher mc rate.

My tests have stayed the same since 3 days ago. They are definitely positive, but haven’t gotten any darker at all, and actually maybe a little lighter. I’m actually on my way to the doctor right now.

I’m pretty much hoping for the best, but preparing for another early loss. Ever since yesterday, I’ve had this sharp pain in my upper abdomen. It’s like maybe an inch below my ribs. It’s off and on and in the exact spot still today. Has anyone experienced anything similar to that? It’s probably totally unrelated, but just being cautious.