White fin skin coming from under my turtles neck.?

Shedding is natural and normal for red eared sliders. Shedding skin has a thin, wispy and translucent appearance. Most often it is around the neck and the front and rear legs. It is very easily visible underwater.

EXCESSIVE shedding is not normal and can result from water temperatures being too high, high protein diets, inadequate basking, or fast growth. It could also be a symptom of poor water quality or a developing infection. Proper diet and water conditions will help avoid this.

Could be just a little shed stuck on him. Its not a good idea to help shed reptiles but if it truely looks like shed and he's comfortable with you touching him, tug at it a little and see if its just shed. Don't tug too hard in case its actually part of him T-T thatd be painful