I have been experiencing chest pain off and on for the last 4 months. The doctor says it is costochondritis. Can costochondritis go away and then return weeks later? The area between my breasts is now swollen and really hurts. Also, the pain will sometimes radiate to my breasts. In addition to this, the doctor did some blood work and determined I have a recent mononucleous infection. I m not sick (no fever, no sore throat, etc...). So, is it possible to have mono with no symptoms and as an adult (39 years old). I had aches in my legs and now that is gone.