Hello! i fell down the stairs 2 days ago, and i have a cut (5/16" long) on the lining between the gums and the inside cheek wall. what to do?

Nothing: this will heal on its own. Avoid spicy foods for a few days and rinse after meals.

Cut on gums: If the cut is not too deep, in most cases it will heal on its own. Make sure you don't aggravate it ( chew away from it), keep it clean...rinse with warm salt water 2-3 x a day. That being said, it's always best to have it examined by a dentist to make sure it is only a cut and there was no damage to the underlying area and teeth. If it doesn't heal in 5-7 days, have it examined.