Thanks for posting your query.
As your condition is responding to Surfaz SN cream, your condition could be either due to yeast infection or due to some irritants like soaps or antiseptics.
If it is due to Yeast infection ( your Dermatologist will able to diagnose with examination and investigations) you have to take systemic antifungal antibiotics for 3-4 weeks along with topical application. It will be completely alright. If you are sexually active your partners also should be treated simultaneously. Then only you will not have the recurrence.
If you are a diabetic it has to be controlled tightly and if you are on drugs like steroids
that has to be tapered.
Avoid using soaps and antiseptics inside your foreskin of penis. You better consult a dermatologist
and under his/her guidance you will be alright soon.
Get well soon.