Denise, IPE is rare . . . although I wonder how many undiagnosed cases there are. And I'm not surprised that they are finding nothing wrong with you, because that's the case with the majority of IPE cases that survive.
I find this particular medical entity quite frightening, because it strikes out of nowhere, strikes healthy people, does not require depth to occur, and can be lethal. And it's rare enough that we don't have a lot of information about recurrence. I don't remember having seen a report of someone getting it a second time, but that may well be because people who have had it don't dive any more.
I spent a lot of time reading up on this, when I first heard of it, because I remain convinced it may well explain some of the otherwise inexplicable diving accidents -- the ones where everything seemed to be fine, until it wasn't.