Thank you for posting your query on HCM.
Since you have not mentioned relevant history like age, duration of condition, use of medications(oral and creams)/cosmetics/alternative medicines etc it is difficult to reach definitive diagnosis without proper examination.
From your description, the most probable condition you may be suffering from is acne vulgaris
which can occur at any sites of your body including your buttocks.
Acne/Acneiform eruption is common condition due to inflammation of your oil-producing glands(sebaceous glands) and pretty amenable to treatment.
Firstly, avoid any ayurvedic/homeopathic medicines/powders if your currently on them.
Avoid use of talcum powder and moisturizers in those areas.
Secondly, start taking oral antibiotics
and solution containing clindamycin twice a day and a gel containing benzoyl peroxide
/adapalene at bedtime.
You may also add a soap/ containing tea-tree oil or benzoyl peroxide.
Hope this will take care of your problems.
Wish you best of health.