First you might want to check the possible side effects of the medication(s) you are on. If itching isn't a side effect you should get a CBC as it could be a liver problem as stated above.
Please don't freak out about the liver stuff. I work in the medical field, so my brain is trained/brainwashed to the clues. The good thing about the liver is that it's a very forgiving organ. My son's liver enzymes went off the chart when he upped his 6MP that he takes for his Crohn's. He lowered his dose and by his next labs things were back to normal.