The issue of iron is a good possibility. I'm not officially anemic, but after a weird issue with my period (we're talking two and a half weeks of nonstop flow) I've learned what iron deficincy feels like. I now pay attention and when I start feeling a little droopy, I get in a nice, juicy steak. Works wonders for me, and would be an easy thing for you to try. Of course, since you already have an appointment, it's a bit moot.