Tretinoin may make your lips more dry and peely...at least that is what it does to other areas on my face. However, it is possible that vitamin A deficiency may contribute to EC. I posted an article about patients with Down's Syndrome. They had vitamin A deficiency or vitamin supplements helped them. When I took a vitamin absorption test (this is different from the standard vitamin A blood test), it showed that I was absorbing all vitamins except vitamin A. Vitamin A might have still shown in a standard blood test from the food I ate recently, but not the absorption one.
I think fordyce spots are a result of inflammation whether it be from allergies, bacteria, yeast, etc. Perhaps anti-inflammatory products might help.