Hello and welcome to Healthcare Magic. Thanks for your query.
It is unlikely for a acute tonsillitis
to subside within minutes. However it could be possible that your son must have had an acute irritation in the throat causing him to cry, and which could have soothed and subsided with the throat lozenges. I don't think that this is a specific sign of something worrying.
I hope you that your son has been examined at the Urgent Care facility and advised further treatment. Drinking hot fluids frequently can also help in reducing the inflammation and discomfort.
Dr. Sheeba Stephen