Hi, i've been tired and having a low grade fever at night. today my throat is sore and one of my tonsils looks swollen.how can i tell if it's swollen?

Try using a mirror: It's not easy to see one's own tonsils. Throat symptoms can be from flu or cold viruses, strep throat, allergies, etc., except that allergies usually don't cause a fever. Flu causes fever. Doctors have 5-minute tests for strep. Doctors also have a quick test for Flu A & B. If the problem is influenza, doctors can consider treating with medications such as Tamiflu (oseltamivir). Mono is caused by the EBV virus.