Should i worry about yellowish/brown discharge coming from a perianal hematoma? it has been 3 months since it ruptured.

Perianal abscess?: This type of discharge, for this long, suggests it was more than a hematoma, more likely an abscess. Or if originally a hematoma, now secondarily infected -- but this makes little difference. You need to see a doctor soon for further diagnosis and treatment, which might include an antibiotic prescription, minor surgery for drainage, or both. Good luck!