I have just healed from an internal anal fissure with the help of antibiotics. After how long can I do anal sex? Would sex provoke it to come back?

Anal fissue. Anal fissures are caused by injury (trauma) to the anal canal. You should move forward very slowly, don't rush back into full anal sex. With time you will figure out whether or not you can have anal sex without developing another fissure. Best of luck.