My whole body is aching, what could that be a sign of?

Many Reasons: Body aches may be the result of many reasons. It is wise to see your physician to obtain a complete history and physical. There are many causes which range from infection (viral, bacterial, fungal), hormonal, tumors/cancer, pharmaceuticals/drugs, musculoskeletal, and other causes. Good physicians treat the cause, not the symptoms.

Fibromyalgia: I agree with dr huang but would consider fibromaylgia first.