Jumped into water from a high dive held my nose and loud noise as I hit the water if I remember correctly. And my ear and that whole side of my head feels clogged and stuffy and ear fizzles every time I hold my nose and blow air. Happened immediately not over a few days.
Such can happen if Eustachian tube (the small connecting tube between ear and pharynx) get blocked due to pressure changes or water. But if persistent, there can be other possibilities also-ear infection, ATOM, Tympanic membrane injury etc. you need to consult ENT specialist to get your ear examined