I think i have a anal fissure but when i went to a regular doctor, he looked at my anus and told me he didn't see anything wrong. its not in my head?

Possibilities...: Not all anal fissures are readily apparent on external exam, nor are internal hemorrhoid(s), proctitis (inflamed rectum), anal abscess or fistula, trauma to the anal canal, subtle skin changes around the anus (benign or malignant). Also, proctalgia (of any cause) can promote distress without inflammation.The only way to find out, and to start appropriate treatment, is to get a thorough exam.