Hello,
Thank you for posting in DoctorSpring.
An abscess in the peri anal region has to be drained surgically if it is large. Since you had expert opinions from Surgeons I assume it is small enough not requiring any drainage. It is normal to experience some pain while on antibiotics.
Antibiotic like Augumentin may not act in some circumstances if the bacteria is not sensitive. This has to be kept in mind and discussed with your Doctor if the symptoms persist. So even after the stipulated time if the symptoms persist consider drainage / change of antibiotics
Masturabtion should not cause aggravation of the symptoms.
Wish you speedy recovery
Regards