Thank you for your query.
If the behaviour of your son of sleepwalking is of recent origin then I suggest that you discuss with him his relationship with his peers and brother. Something must be disturbing him which is playing in his mind at the subconscious level.
For the sore throat
and enlarged tonsils you can give him some decongestant/cough
medicine and steam inhalation. In case there is no improvement in the next day or two it is advisable to consult your doctor.
I hope I have answered your query to your satisfaction.
Wishing your son all the best.