Thanks for writing to H.C.M. for your query.
I have gone through your query regarding severe pain
in throat of your father due to tonsillitis. He is taking opiade pain killer but at present that is not able to relieve the pain.
After thinking about your problems it appears as your father is chronic tonsillitis
with ulceration or some other associated pathology, so it will be better to consult an ENT secialist for thorough examination and accordingly treatment may be plan.
At present to get immidiate relief he may do gargling with viscous xylocain, this will not cure his disease but will relieve pain only till the effect of medicine.