I have frequent sinus infections with a history of nasal polyps. It seems as if dairy worsens my sinuses. Is this common? Does this mean I'm allergic to dairy? Should I have food allergy tests completed?

Not necessarily. Many people report increased mucus quantity or thickness when drinking milk. This is not due to an allergy. Milk allergy rarely present with isolated nasal/sinus congestion. If fatty milk is triggering reflux, it can indirectly increase congestion. If you are concerned, i recommend testing, but don't be surprised if the testing is negative.