Recently, i have been coughing for three days. is it just allergies?

Hard to tell: Cough can be due to a number of conditions. A common cold or upper respiratory tract infections is probably the most likely cause but poorly controlled allergies, asthma, and/or GERD can also cause issues with persistent cough. If you have increased post-nasal drip from allergies this is likely contributing. Try symptomatic management. See your primary doctor for further workup if persists.