Boils are minor outermost(superficial) skin infections. Perianal abscess is collection of pus due to infection in and around anal opening.
Perianal fistula is a separate abnormal tract from anus to skin due to chronic constipation, fissure and infection.
Identifying it should be by a doctor preferably a surgeon.
Next Steps
Perianal abscess and fistula both require surgical treatment and usually take 5days to 2 weeks for u to resume your regular activities. It depends on the size and severity.