Usually physical pain is your body's way of alerting you to a deeper problem. Sometimes it can be as simple as being dehydrated -- when you don't drink enough water your body is unable to eliminate waste which can cause achiness throughout the body; also since the body is around 97% water you can see that adequate water (not juice or soda etc) is needed for every bodily function. You might be lucky and just drinking a glass of water every hour and getting some rest (while the girls are napping) will make you feel much better.
Lack of sleep and lack of water are the two most common causes of aches and pains and overall "not feeling good," as well as not getting enough raw vegetables and salads: when the body doesn't eliminate all the waste, it begins to putrify and sends out toxins that get into the bloodstream and cause problems throughout the body.
By the way, keep in mind that anything at all that you ingest ends up in your breast milk and therefore into your baby, so I would avoid at all costs taking any meds.
These pains might also be a symptom of something more serious, such as problems with your IUD... it could also be a reaction to something you ate... but try the water-and-sleep treatment and see if that helps.