Knot=get it checked
Any lump which sticks around for more than a week deserves a medical exam and likely a biopsy
A knot in the cheek could be any number of things, most of which are benign however. Ulcerations or sores on the skin or in the mouth/throat are very concerning, especially if you have a lump or knot anywhere in the head and neck. See your local ENT asap.