strep throat has some of the same symptoms as other illnesses. because of this, it can be hard to know if a person has strep throat without a throat culture or rapid strep test. if the person has fever and sore throat with coughing, a runny nose, diarrhea, and red itchy feeling eyes, it is more likely to be a sore throat that is caused by a virus. infectious mononucleosis can cause swollen lymph nodes in the neck and a sore throat, fever, and it can make the tonsils get bigger. this diagnosis can be determined by a blood test. there is however no specific treatment for infectious mononucleosis.