Thank you for your query.
ulcer can take 6-8 weeks to heal. If the duration of the ulcer has been longer than this then it shall be advisable to give your son a course of INH.
You son needs to be investigated for the low haemoglobin
and the high eosinophil count
which may be unrelated to the BCG ulcer.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal