Inhalers not helping at all with DS' cough

[coffeecake]

Hi DS has had a cough for 7 months which started with a bad cold and cough and lingered.
It's not too bad (ie some days he doesn't cough at all or maybe just once or twice) but it's still there.
He's been prescribed 2 inhalers (brown and blue) and they don't seem to help at all.
He's been on the brown one for a month now and there is no improvement and the blue one doesn't do anything at all anyway.
I'm wondering if his cough could be triggered by something else than asthma, as he's fine some days and then suddenly he would start coughing, almost like if something he's breathing in is triggering it and then not cough at all for the rest of the day.
I have seen 5 different doctors about this and they don't seem worried at all and just put it down to asthma.
Would it be possible that it could be an allergy of some sort?

PS: He never ever coughs at night.

The blue one is probably a salbutamol inhaler. My DD had this and it didn't do much for her so the doc changed it to an atovent inhaler - different stuff inside. Worked well for her, perhaps you could ask?

Also for a cough of that duration, you should get a chest x ray. My DS had a cough for 4 months and he got a chest x ray.

How old is he? Children I hvae referred to are DS (4) and DD (2)

DS is 4. Yes I will be pushing but the last time I said to the doctor that the brown inhaler didn't seem to be helping much either he said "yes but he hasn't been on it for very long, give it another 2 months".
The cough isn't chesty by the way.

Yes it could be a possibility as he is extremely picky and often gags on food.
I will have it all checked out and ask to be referred to a specialist.
Actually I guess the title of my post was a bit misleading, when I said "inhalers not helping at all" what I meant was "not helping much".
In other words it has made a bit of a difference (ie there was a very very slight wheeze when he slept which seems to have disappeared, not coughing anymore when out in cold weather or exercising) but the cough is still there.
I would have thought the inhaler would have eliminated it.
Sorry I was a bit worried about it this morning and a bit cross against the doctors so I might have over exaggerated my words due to my emotions .
Thank you for your replies though (Pixieonaleaf a star as usual, you have helped me before with this issue)
It's just frustrating me a bit that I don't know for sure what it causing it.

Not being funny, but is he taking in the medication properly?

I only say this because as an adult, I have just changed from a standard puffer type to a thing with capsules inside, and it didn't seem to be doing its job. Then I read the instructions and I wasn't holding it in for long enough [sheepish]