I have a cold sore for 1 month. it is on the corner of my lips, so if i open my mouth by eating, yawning, it cracks again. wound doesnt seem to heal. what should i apply there to heal? is zinc cream ok or best to stick to acyclovir? or what else?

A “cold sore” is a herpes simplex infection. Usually lasts 5-10 days. 1 month is unusual and therefore maybe something else. Rather than switching randomly from one med to another, would have a physician observe and offer a alternative diagnosis. BTW - zinc cream is a great sun protective and may prevent new outbreaks of herpes, but does nothing to cure an outbreak that has already begun