Thanks for placing your query through HCM.
I can appreciate your concerns.
on Friday night was most likely the result the tissue injury/inflammation on the tongue caused by minor surgery.
The current fever can be caused if the tongue wound got infected (more likely if there is renewed pain/swelling/discharge or foul smell), or it is quite possible due to some unrelated cause.
Please see your doctor & clarifications as he can examine you boy & can give more confident answer.
Hope I have answered your query.
Wish him good health.