This is a typical case of acne vulgaris
affecting the trunk. few things can be done for him
1. use some anti inflammatory drug to relieve him of the pain but should be taken with a doctor's advice. and specially after meals.
2. he should not prick any of the lesions as it will worsen the disease and will increase the infection.
3. use some anti acne soaps that will help to reduce the excess oil on body.
4. consult your nearby dermatologist
as he may need an expert opinion based on the type of lesions and duration of his illness.
Dr Gaurav Bhaskar