Rap, what did your clients say when they quit?

I would pick one thing and work on that. Do you have a light for your SAD or are you getting outside some; I would start taking a 15 minute walk on break at work. A woman I worked with did that, walked around the buildings in the morning and then in the afternoon. Go to your regular doctor and get the SAD diagnosis, that's not something one "believes" in but something that just is and can be worked with and made better. SAD responds to enough sun/light, that's what it is.

But pick one of the problems you have mentioned and work on it. You say you are scheduled for work the entire coming month. Pick one day at random and tell them you're taking a personal day. Then plan that day so you're doing something "fun" as well as getting a chore or two done. Sleep late deliberately, get your hair done, something for you.