Thank you for your query.
From your post I understand you are seeking views on:
1. Flat feet
2. Subcutaneous nodule
3. Enlarged tonsils
As your son is already on an antibiotic for his throat infection
and enlarged tonsils nothing else need not be done at present. Once the infection gets controlled the tonsils should return to normal size. If they are not causing any other obstructive problem then nothing needs to be done.
Flat feet should not be a problem in your son's daily activities. Under orthopedic surgeon a physiotherpist can guide necessary exercises to help your child.
Swelling in the knee joints and subcutaneous nodules on the finger and thumb need to be examined by a doctor and managed accordingly. Without coming to know the exact cause of the swellings and nodule it is difficult to give a prognosis.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.