Thanks for posting your query.
I will be glad to be of assistance.
From your description he seems to have developed an abscess
. An abscess needs urgent treatment.
I would recommend a course of oral antibiotics
. However a prescription will be needed for the same.
Also he needs to take a pain killer like paracetamol
since he gets pain on walking. An abscess may sometimes have to be drained as well.
Please let me know if you have any queries.