Lower back pain?

Does anyone get a pain in your sacrum when taking oxycodone? Sometimes when I take the medicine I get a lower back pain that is exaserbated when I bend over to pick up objects. I only get it when I have been taking oxycodone for a few days.... It it like the mast cell itch that some people develop? Its horribly painful and I am not sure why I get this sometimes when I take this medication.