Itching is a nonspecific symptom. In other words, it can be caused by a multitude of things. It can be caused by something that you consume by mouth (such as food or medication), something that you breathe in (such as dust, dander, pollen, or mold spores), or something that you touch (such as detergent residue or fabric sizing on clothing or bedding). Your big clue is that it started shortly after your surgery. I would try to identify something that changed in your diet, your medications, or your environment around that time. If you were placed on any new medications subsequent to your surgery, I would take a close look at those. Consultation with your pharmacist might be helpful. At some point, you might also want to consult an allergist. Good luck.