Primary care physician tell if you have allergies if they never ran a allergy test on me. my nose is swollen on 1 side and left side is red.

Why not?: Most diseases are diagnosed by the history & exam findings. Tests are usually done to confirm or disprove a tentative diagnosis. I can tell within >80% certainty that a patient has an allergy problem or not with the history and exam. Allergy testing is a way to pinpoint the allergens triggering your symptoms and formulate a plan to treat your condition (avoidance measures, allergy shots etc).