What Causes Persistent Fever In A Toddler?

My little boy 22 month had a fish bone removed from his throat on Friday night at hospital with analgesic , but tonight he has high temp 39.5 given calpol and ibuprofen but temp hardly going down , the lowest one is 38,5 after 1 hour and 15 min given the calpol and ibuprofen, I just wanted to know also if the fish bone has given any side effects because it didn t stay that long in his throat it was removed after 6 hours when he swallowed! Thank you ! Please can you give me some advice , if the temp is from fish bone as left any side effects when it was removed ?