I would definitely add a multi-vitamin. Calcium supplement too. On a reduced calorie intake, it is really hard to get enough of each nutrient. Particularly if your diet tends to be a bit repetitious.
If you aren't drinking at least 64 oz. of water, I would up that as well. I am for 72 - 84 oz. if I can manage it every day.
It may be an eletrolyte imbalance. Make sure your eating a lot of fruits and vegetables. A vitamin pill isn't going to help that. Are you on a diuretic such as HCTZ or Lasix? Blood pressure meds? I suppliment with Calcium and magnesium. I get a vague crampy feeling with my potassium is off.
I would suggest that you get some physical activity if you are able--taking walks is often good. It doesn't have to be anything super strenuous, but it might help you to feel better. Some folks also like the Walk Away The Pounds videos as a way to get started. You can sometimes find these at your library.
Muscle pain
