Pulmonary function tests

I'm assuming there are ppl on here that have had pulmonary function tests. So that I don't make this a horribly long post, I'll just post questions and if anyone knows the answers, great!

1. Under what conditions would a person not be able to do the methacholine challenge?

2. I've been asthmatic since I was a toddler. Is there any reason why my tests would be "normal"? Remember i was unable to take the methacholine challenge, for whatever reason.

3. Without the methacholine challenge, does it change the rest of the pft's for the purpose of confirming an asthma dx?

4. Do the pfts change with a flare?

Thank you! My asthma was somewhat controlled when I had my test, and that was 4 months ago I've progressively gotten worse and it upsets me that that test shows normal results. it doesn't make sense. Somebody please help me make sense of this. Thank you!