IMHO I wouldn't say that it's "normal" to lose kids. And despite doing our best by our animals, sometimes things just happen... For more details,
@SkyWarrior lost (I believe) 5 of her 7 kids this year for completely unknown reasons... Even the necropsies showed no definitive reason for the deaths. Just playing devil's advocate here... On the other hand, it is ALWAYS a good idea to promote due diligence and try to dig a little deeper to find out if there's more to the story... For being such sturdy animals, goats can die very quickly from the darndest circumstances... and it's more the case with young kids.

and wishing you the best with your goats
I heard my name taken in vain.
Seriously, there can be some pretty bad years, IMO. Last year, I would've said "no way would I buy from a herd that lost that many kids." Now, having experienced bizarre weirdness in my own herd, I have to at least ask "what did each one die of?" That seems to be the million dollar question. In many cases, you'd be able to point to something that seemed to suggest a common cause. My own experience with kid deaths was there was no common cause.

I just had a really bad run of bad luck that I think was probably due to late kidding combined with awful temperatures. Each of the kids I had die died from something totally unrelated to the other. The vet even said, "I think you just had bad luck." So, I'm a case where that can happen.
Pneumonia can be bacterial related, and from doing some research on that for an article, there are vaccinations for it. That being said, I've always heard CD&T and maybe CL. If I had issues with pneumonia, I'd consider that vaccine.
My own experience and the experience I've heard from a rancher is that while goats are exceedingly tough, when they go downhill, they seem to drop like flies. Any little thing you want to be on top of quick. Digestive ailments can hit fast and kill. Even then, when I was on top of the problems, I still got bit.
No, I don't want to scare you. Chances are your kids will be fine. Just find out what happened and make up your mind if it's something that can bite you.
Oh, and
