I agree with the hot toddy recommendation as well as warming his apple juice or any other juices. Make sure they're just warm, not hot. It will soothe his throat and feel much better to swallow. If he hasn't already, now is the time to introduce him to chicken noodle soup, jello, pudding and yogurt. The ibuprofen is VERY important! My house is dealing with strep -I just got my first diagnosis this morning after almost 41 strep-free years! I feel for your little one because swollen, sore, pus-filled throats are truly agonizing. The warm stuff and ibuprofen does help immensely. Does he gargle yet? My oldest was gargling at 2 1/2 and understood to spit, but my youngest doesn't get gargling yet, and he's currently 2 1/2. IF your son will gargle and spit, give him some warm salt water to gargle. That will also help. It also won't be the end of the world if he swallows a little either.
Also -IF he gargles and spits and you can count on him to do it, ask the pediatrician for "Magic Mouthwash." It's a prescription of lidocaine, and I think she told me something nuts like mylanta and another over-the-counter. It's very sweet, but it numbs the mouth and throat for awhile. HOWEVER, due to the lidocaine, it's dangerous if he swallows it in any quantity ( a little is okay), but he can't gulp his sip down instead of gargling. Only ask for this if he truly is gargling and spitting. You could also try Chloraseptic spray. It deadens as well and I grew up with that getting sprayed in my mouth constantly!