Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain pimples outside anus can occur due to causes like Herpes virus infection causing cold sores while can also be due to hair
follicle infection or folliculitis or due to
allergic reaction or
contact dermatitis..
It can be treated only once the cause is confirmed and for this you need to
consult a Dermatologist and get evaluated and a thorough clinical evaluation and investigations like microscopic examination of the scrapings from the lesions, blood tests etc can help in diagnosis and treated accordingly..
In case of herpes virus infection antiviral medications like Oral and Topical Acyclovir can help..
In case of folliculitis as it is caused by bacterial infection
topical antibiotic ointment along with steroid ointment can help..
For allergies ruling out the cause of reaction and avoiding exposure to it along with anti allergics like Levocetrizine can help..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora..