5mth old with suspected asthma

Hi there I'm new I have a 5mth old baby boy with suspected asthma although apparently he can't be given a definite diagnosis due to his age? He has been given a blue inhaler with spacer and mask and been taking that a number of weeks now but things are getting worse. He coughs at nigh (not a croupy cough) and can't breathe, he's also really wheezy which he has been since born again at night. He hates going to sleep at the moment and I really feel this is because he knows he's going to cough and be ill.... Last night we had the paramedics out Our little boy already has pulmonary stenosis (narrowing of valve between heart and lungs) and we know this isn't connected to that he also gets really breathless on bottle which earlier on meant two weeks in hospital when he had failure to thrive. With regards to his breathing I feel we are very much fobbed off and very much alone. I spoke to a really lovely asthma uk nurse this evening and going back to gp in morning but I don't have much hope they will do anything more for him. Anybody offer advice?