Border Collie in need of help

Hi,

My Border Collie dog is having respiratory problems. She went into repiratory failure a month ago and went to the best vets possible- but after spending several thousand, we were told that she is too healthy for the conditions that would have brought about this episode.
More in depth details:
1- age 5
2- whole female
3- had an allergic reaction to daisys about 3 years ago. This made her eyes swell (looking like a bubble fish) this went away once identified.
4- she has a high pitched bark
5- she is prone to gaining weight. only effective exercise to combat this- swimming
6- episode happened on a rainy day in the bushy areas of Perth.
7- after 40 minutes of relative easy - moderate walking, she started rasping.
8- by the time we got back to the car, she had very thready breathing
9- got to vets about an hour later
10- vet administered steroids and anti-histimine.
11- had no affect, administered oxygen, then went to after hours hospital.
12- cardiac arrest upon arrival.
13- she was saved and put on oxygen for two days
14- had every imaginable test. echocardiogram, blood tests, oxygen levels from artery, x-rays, camera down the throat
15- sent home with an inhaler
16- no test revealed anything
17- laryngeal paralysis was looked at as the fore-runner, but her larynx was within normal limits, but was at the lower end.
18- still breathing with a raspy sound after exercise
19- occassional cough, dry non-productive
20- oh & she seemed to have nasal discharge before this episode, which stained her nose at the sides, this was pointed out, but none of the vets seemed interested.
21- diet- organic, cooked & raw foods, incl veges, fruits, chicken, beef & fish, pasta (though not much)
After this harrowing experience, I am hoping that someone out there may be able to help- PLEASE!!!!

Thanks, Shelley