I'm very sorry to hear that. Obviously your stress levels will now be past red-line, but there is a positive side to finding a specific cause.
Diagnostics are much, much more difficult when nothing reveals itself after tests. It's now a case of riding out the 'not knowing' period.
I would assume your case will be dealt with very quickly - no significant delay is acceptable.
I, and I'm sure a lot of forum members, will be thinking of you. Pleas let us know how things proceed.