What are the chances that a red, itchy, burning scrotum skin is caused by roundworm? i was given ivermectin+albendazole tablets by doctor but no help.

Probably: This is probably pruritus scroti. Please see a dermatologist for treatment.

Yeast Infection: That surely does not sound like an effective medication treatment for a common yeast infection. There are numerous anti-fungals to use and even in india, i believe, they do not require a prescription.

Not worms: I was not present for the office visit but I agree with my colleague that this sounds totally inappropriate. Most often this is tinea cruris, best managed by a combination of topical over-the-counter antifungals, washing several times a day with a clean towel each time, and keeping things cool down their day and night. Best wishes.