mine is like that too, but her dots aren't red they are white (same colour as her)
And I can't find out what it is!
(P.S. We also have a 3 year old Oranda, 3 Cory Catfish and 7 guppies who like each other and another water snail who is fine. But I fear if this is a rare disease it mite affect the other snail and maybe the fish too! I NEED HELP!!!