Have you been checked for any autoimmune diseases?

Sounds like it could be something like Celiac disease.

From what I've seen, most of those are potential Celiac symptoms. But I imagine other autoimmune diseases could also cause these types of symptoms.

This graphic [0] shows some potential Celiac symptoms. A guy surveyed a bunch of people with Celiac for their symptoms and listed the symptoms given more then once. The orange ones are the most commonly given and many of your listed symptoms would fall under the orange ones.

The abdominal pain is especially what makes me think it could be Celiac vs. other autoimmune diseases or something else.

[0] - https://glutendude.com/wp-content/uploads/2021/02/celiac-dis...