Had annal fissure, recovered but came back again due to antibiotic induced constipation, drinking enough water, laxatives and fibres.recently applied warm boroline to treat but after that my annus became tight and passing gas is becoming a problem?

You're apparently having some spasm of the anal sphincter which can occur if the fissure extends into the sphincter muscle. I recommend consulting a proctologist to help you get proper healing of your anal fissure and also provide good follow-up. In the meantime apply hot compresses. Try massaging the anal area. There may be a muscle relaxant cream that the proctologist may prescribe.