Oh man, the mask thing. Took my first trip to asia recently and was totally weirded out by it. Not that I've never seen them...growing up in Vancouver you see them all over the place. Much like the Asian grannies with sun visors. What you don't see is them en masse.

Spent some time in Tokyo and 5 days in Seoul and wow, these things seemed to be on 2/5 travelers. I couldn't decide if they were sick or trying to avoid getting sick by other people, OR a combo!?

I'd say you'll get jack squat from Ryanair, get a doctor's note from the GP like a get out of work free card and then call the insurance guys. If they are able to make a decent offer, then decide if there's no offer, then depending on how much money you're gonna lose, you'll have to decide.