I'm on similar meds for a similar condition. My cardiologist told me to stick with Tylenol for headaches, etc. and not to use additional aspirin or other NSAIDS like Advil. They could increase your bleeding risk which is already increased with the aspirin and Plavix and there may be (I stress the word may; no one really knows) some indication that some of the OTC meds like Advil could have an impact on heart health like Vioxx did. (removed from market recently).
But the Vytorin may have an impact on your liver function, and so might Tylenol, so be sure to ask your doctor which one(s) he wants you to use.