Oversanding created black triangles

Hello everyone,

Throughout my treatment I had the impression that my dentist did not have great expertise/was not a good professional. She did IPR in many appointments, and I had the impression that she was overdoing it. Now, with the treatment completed for a couple of months, I noticed I have some black triangles that I did not have before. This is courcining me a lot, since I get food stuck between my teeth every single time I eat, which is kind of embarassing.

Has anyone gone through something similar? Since it has only been a couple of months, is it possible that these gaps will disapper? Should I seek treatment for black triangles?

Thank you!