I have a sore throat and it hurts to swallow. I don't have my tonsils. What could it be mono, strep and what can I do for pain?

Comfort measures. Assuming you don't have a lot of other symptoms, the following may help: gargling with warm water with salt (1/4 teaspoon in 8 ounces); sore throat lozenges such as cepacol; sore throat spray such as chloraseptic; a teaspoon of honey as needed; and pain reliever such as Acetaminophen (tylenol). If your sore throat is accompanied by other significant symptoms, please seek medical attention.
Viral infection. The symptoms sound like a viral pharyngitis (infection of the back of your throat). These symptoms may require 10 14 days to resolve. In the mean time, over the counter pain meds such as ibuprofen, advil or alleve with plenty of fluids should help. It is unlikely mono and a culture would be necessary to rule out strep.