7 month old and breathing?

So the other night DD got very upset i was all alone driving back roads had no where to pull over and had 15 minutes till a city so i tried talking to her singing. Well by the time i got to the city i got in the back seat and took her out of the carseat held her nursed her tried to calm her down she fell back asleep put her back in her carseat and drove another 40 mins home. It took her about and hour and a half to calm down completley, even in her sleep

You know how a toddler gets worked up and there still upset and trying to calm down and cant catch there breath?

Thats how dd was in her sleep i called the dr and no one returned my calls ive been calling everyday and finally got an appt in for Monday

The dr said it could be a heart or lung issue i try to not let her get upset but sometimes she just feels the need to cry.   any advice? She has made herself throw up idk what the all of the sudden she hates the car seat