Your contact dermatitis diagnosis could likely be due to a chlorine sensitivity, developed over time with your frequent exposure to chlorinated pool water.
If this is the case indeed, the chlorine stays on your skin, even after showering and continues irritating and oxidizing your skin.
There's a Vitamin C based spray (with anti-oxidizing action) for swimmers called SwimSpray, which might help
lessen or eliminate this type of issue.
Just do an online search.
Best wishes,
Niko