Being that flowers and blossoms just started blooming, how can a person tell if he has allergies, a cold, or the covid-19 corona virus?

Can't tell for sure: People with itchy-sneezy allergies catch colds and COVID-19 too. To avoid catching respiratory viruses (colds, flu, COVID) during the flu season, a person can avoid crowds or can wear a mask in crowded areas where sick and well people mix. Face masks work by blocking most of the airborne particles and by acting as your sleeve when you cough or sneeze (so you don't have to look for your sleeve).

Testing diagnoses: Allergies can present w stuffy/ runny nose, cough, sneezing, sore/ scratchy throat or itchy/ watery eyes. Symptoms of COVID 19 infection may include (but aren’t limited to) dry cough, shortness of breath, nasal congestion, fever, headache, sore throat, feeling tired, loss of sense of taste/smell, decreased appetite, nausea, diarrhea, vomiting, chills without or without shaking & muscle aches.

It is true that a person can't always tell, especially now with Omicron, which causes more upper respiratory symptoms, if there is any suspicion of COVID-19, please get tested and discuss with your doctor. If you have a history of allergies and your allergy meds are working, it's probably allergy. Wearing a mask when around others and getting vaccinated are the best protections & stay home if ill!