Thank you VLBUltraHot! I agree, she is very cute!
We've had her looked at (multiple times), endoscope too I believe, and there was no sign of a bacterial infection. We had her tested and found out that she is quite allergic to wheat, soy, and wheat, and a tiny bit to carrots. We changed her feed because it had oats and soy in it, which stopped her coughing, but then she started up again recently and we haven't had her looked at yet. We put some kind of supplement in her feed (I don't remember what it was called; my cousin gave it to her. She owns the barn and she knows more about horses than I do.) and she doesn't cough much, if at all, anymore. She's fine for now and we'll probably be talking to the vet in the spring about it.
GoldenHorse, I would never consider breeding just because someone else thinks it's a good idea. If I thought I wasn't ready, or Destiny couldn't handle it, or the foal wouldn't be worth bringing into the world, I wouldn't even be considering this. But I'm overly cautious for a lot of things, especially concerning my horse, and if I think I'm ready, then I am. And I will be speaking to our vet about breeding and see what she thinks, don't worry. :) I know actually breeding is way different than just thinking about it, and I have thought a lot about it, for years now. This isn't just a spur-of-the-moment thing. It's been a long time coming, in a way. I wasn't ready for it before, but I am now.