Basically they keep your ears from flooding. For cold water and surfer's ear (exostosis) this can be very useful, the main reason I use them. Since they do keep most of the water out of your ear, when properly fitted, this can be extremely helpful for outer ear infections on tropical vacations. I still use ear beer as an added precaution.
(note-on the Lembeh trip an extremely experience diver, dives almost every day in cold water, did not do ear beer or other precaution, got an outer ear infection, and missed about half the dives along with being miserable. That's an expensive mistake on so many levels.)
IMO, their claim to facilitate clearing is not viable. I see no help at all, nor any hindrance, but still consider them to be an extremely useful diving tool.
It sounds like you had a clearing problem, did some baurotrauma, and suffered the consequences of that. I'm not sure the Proplugs would have helped your particular problem.OTOH, they are cheap and properly used won't hurt you and can help. Why NOT try them. They've been around a long time and are a viable product.
What did the ENT say? What diagnosis, treatments, precautions, and advice they give you?