It could be withdrawal - it depends what you were eating before and now. I was eating tons of sugar before and I know it took me a few days to feel better.
Quality wholefoods make me feel better. I am finding I have to keep self-talking at the moment to keep myself on track! LOL...like being my own coach as it were : )
Its great that being taller you can have more calories! It does make me irritable that I can eat so few at less than 5'2".
I am feeling a bit that way myself today as I ate too much yesterday and am trying to be extra-good today as I don't want it to turn into a slide. I don't want to undo any of the progress I have made.
What is your workout? Could you do something a little gentler on yourself until you get some strength up?
Don't give up...stay here and get the answers - I have found a lot of inspiration from lurking for a while!
(am trying to post more!)
All the best!!