Sorry you're not feeling well. I hope your doctor is able to help you get some good information as to what is going on.

I lost a lot of muscle weight due to the stress of my first year of grad school. I was probably 15-20 lbs. under what I felt was my optimal weight. Normal for me was 105-112 lbs, I went down to about 92 lbs at my lowest. It definitely did not feel like a good place to be, like what you described. I fatigued easily even though I was making a point of getting good nutrition and good sleep.

Nothing wrong with me at the doctor, the only thing that stood out was my blood pressure was 10 pts higher, but still in a range considered low.

It took a while for me to build myself back up. I think it was a wake-up call for me to take better care of myself in general, and to not let my life get out of balance.