That type of pain is described by a lot of people. Part of the side effects. But anytime I have something that I don't know for sure wht it is, I call and describe it. It may be nothing, and usually is, but if they think it's something to worry about then they can do some tests.
Try not to worry about it too much, I know it's hard not to, but lot's of people describe that pain. Still call your doc.
Hope your doing well otherwise.