My 8 Month Old Son Has Become Extremely Fussy Within

My 8 month old son has become extremely fussy within the last 2 days. He has had a fever of 100-101.4. I have been giving Tylenol with little to no results. His cheeks are red, seems more tired. Doesnt seem to have a good appetite. I noticed one small sore below the lip but was unsure if it came from the drool.