Re-thinking working

I posted the other day that I was upset that the MD wouldn't release me to work.  I have been thinking about it and have begun to question whether or not I really can work.  My ego says yes, but I have to remember that the reason I quit my last job was due to the fact I didn't feel safe practicing my profession.  What makes me think I'm "all better" now?  Not only am I on the same meds, I'm on more than I was then.  I am dopey most of the time.  Some days I take my meds and I don't notice a thing.  Other days, I can barely keep my eyes open.  How am I going to work consistently?  I will discuss this with my NP and get her take on it.  The only reason in the world I even took the job is because we are broke.  However, with some changes, we will be OK without my income.  Really, we will.  I know I need to concentrate on getting myself well, but I still feel like a failure.  I really don't think I can work.  I really don't.  I feel really bad that I took a job when there are so many questions as to my ability to perform.  Why did I do that?  Oh, yes.  That implusiveness that haunts me.  I think I'm going to take a nap.