My 3 year old has a runny nose its clear and cough , and fever 102.6 . not sure if its allergies or a cold . what should i do ? allergy medicine?

Likely a virus: A mild fever from allergies is possible but 102.6 is higher than i would expect. Most likely this is a viral illness and will resolve in 24-48 hours. If your child is complaining of headaches, sore throat or ear pain i would make an appointment with his/her doctor tomorrow.

Viral or StrepThroat: Mild nose and throat symptoms can be from cold viruses, strep throat, allergies, etc., except that allergies don't cause a 102.6 fever. Doctors have rapid 5-minute tests for strep, so a primary care doctor can diagnose strep and start antibiotics "right away", which means within the first 3 days of a strep throat infection.