i have no way of accurately diagnosing your child over the internet -- this would require a hands-on examination. however based solely on the symptoms that you have described it has all the hallmarks of a viral upper respiratory infection. there are hundreds of viruses that can cause these symptoms. the good news is that it should only last a week; the first 3-4 days are the worst and often has the fever. you are treating him appropriately.
4 y/o w/ sore throat & 100. 4 fever went away after tylenol. gave a warm vapor bath also has a stuffy runny nose. monday night sore throat. gave tylenol and went away by morning. tuesday came the runny stuffy nose. gave her a vapor bath and chicken noodle soup. tuesday night sore throat again and gave tylenol. better this morning but still has runny stuffy nose.