I am not much help but about 2 weeks ago my GP diagnosed my DD with Asthma which upset me also as she was in hospital when she was born for 3 months due to repitory reasons. Well she was put straight onto a pump with chamber, 2 pumps, 4 times a day. Well last Thursday I saw my DD's Neonatologist that oversees her medically and she proceeded to tell me that my DD does not have asthma and that she is just taking a while to get over a chest infection she had. She also told me that at my DD's age it is very rare for Asthma to be diagnoised. It has really made me 2nd guess my GP. I am not share what tests out there for such little people. I am lucky to have a respitory specialist working on her medical team, maybe you could ask for a referral to see one for your DS?

ETA: I was a bit slow typing... I am glad Smickers popped in .