How can i treat a small cut on the gums behind of my back tooth?

Cut on gums: The gums heal quickly so if is a cut if you keep the area clean the cut should heal in days but if it is there for a while it may be more serious and you need to have it checked out sometime covering it with an ointment can make it feel better.

Gum irritation: You can get some over the counter product such as orajel to give you some relief. Warm salt water rinses help as well but the cut will heal on its own. You just have to give it some time. During the time it's healing avoid any hard, hot and spicy food to prevent any irritation to the area.