Cow dairy is one of the most common allergens, most difficult to assimilate "foods" there is. It's possible you're one of the many who has a problem with dairy.
Your prescription bottle would tell you if you shouldn't take the meds with milk. It may be that one or more of your medications have lost their effectiveness as well. I have never heard of milk affecting the medications, but that doesn't mean it can't happen. We would be interested to learn what your pharmacist says about this, to educate us all.
For accurate information, call your pharmacist.
Peace
Greenlydia