Have you been tested for POTS? I was diagnosed after several ambulance rides to the ER after getting dizzy out of nowhere and passing out for 5-10 minutes at a time from blood pressure dropping while standing. My POTS was activated by the Covid virus and confirmed by my Cardiologist. It causes me dibilitating fatigue, dizziness, and fainting. Around that same time, I started having unexplained weight loss. I lost 90 pounds before they figured out I had Celiac Disease also activated by the Covid Virus. I have developed several other autoimmune and conditions including fibromyalgia. All which cause chronic pain and fatigue. Because of the covid virus activating all of these things, after nearly 5 years of this, I have a long covid/post covid syndrome diagnoses. You may have been tested for all of this already. But several things you mentioned in your post were similar to my symptoms. I hope you can get this figured out soon.