What is the best way to treat my 2.5 yr old sons cough and fever? it's a very dry racking cough, almost looks like he'd vomit, and 101.5 fever.

Fluids, humidiity: There are not any good/effective cough medicines that are helpful in this age group. Increasing fluid intake will help, as will using a humidifier. Sometimes a spoonful of honey will help settle the cough. If the cough persists, i encourage you to see your pediatrician to make sure there is no indication of pneumonia (esp. Since he's had fever) or any bronchospasm/wheezing needing different meds.