I bought the Dutchess Cup on Amazon, 2 for $15.99. I like them so far! https://smile.amazon.com/gp/product/B00PBJFA3M/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
Actually I have these cups : https://www.amazon.com/Dutchess-Menstrual-Authentic-Original-Cups/dp/B00PBJFA3M
They are FDA Registered too. I’m having the same problem! The swelling doesn’t hurt or bother me in anyway but after using the cup for a day or two I get this swelling ! Can dehydration cause this issue too?