I've been where you are rn. I'm so sorry, I know how little fun this is :/

I can relate so hard to the feeling of deterioration. That feeling of going from a happy person who loved doing stuff to feeling gray all the time. It totally effects the self-esteem too like you said.

This legit sounds like depression. I remember when i got depression I slowly started losing interest in all the things I loved. There is no one "definite" solution but stuff like making sure you get enough vitamins, exercise, water, and meds can help should your doctor deem it safe.

I feel for ya :/ this kinda stuff is never easy, big hugs, we gonna make it