I feel you. I was in a similar place last week, mentally/emotionally. You'll definitely get through this.
I'm glad you're consulting your doctor tomorrow, especially if the meds are contributing to your malaise.
Right now, it sounds you're in a really tough place. Between the recovery diet being restrictive and not feeling well enough to eat, it's like this viscious cycle. The drugs and lack of nutrients/calories make you feel weaker, ill, and can zap your energy so bad it's hard to force yourself to eat/drink. (Sleep all you need to though -- our bodies definitely need that for the healing process!!)
In the meantime, try to remember why you decided to go on this journey. For me, I'm looking forward to less joint pain as the pounds let up, getting my diabetes and blood pressure under control, being able to keep up a little better with my active nieces. Heh, and being able to shop for clothes that make me feel good instead of making me feel hidden.
Are you on any supplements? Chewable multi vitamins and calcium/ vitamin d3 need some time to build up in your system but are definitely helpful in feeling more alive & awake.