Hello uroojj,
Without asking you any questions, it is highly likely that what you have is simply a compulsion. It may seem very weird, but it is very common for people to do things(like clearing or scratching your throat) while totally asleep, obviously being unintentional, and completely unaware of it sometimes. And it is completely harmless to do this.
And I don't want to sound discouraging, but asthma technically cannot really be "cured". People who suffer from asthma will often have quiet periods where all of their symptoms go away, typically for a somewhat long amount of time. But the quiet period varies by person, with some people have shorter quiet periods, others having extra long ones, and even some(possibly you included) not ever having another bout of asthma again. So I guess in a sense, it COULD be cured. And that would be why I said earlier, that it "technically" doesn't have a cure. But either way, I would highly recommend you to start taking asthma medication daily, or in bursts. Corticosteroids would probably be your best bet.
How long has it been since your last bout of asthma?
Any other symptoms or issues you're having?
Please let me know if there is more to your issues, or if it is truly worrying you. I am only going off of what your post said, so there could be more to it than what I've said. So I encourage you to list or explain any other symptoms or problems you're having.
You could consider to practice conscious nose breathing for several minutes and multiple times daily, till your subconscious picks it up and you do it automatically.
Do not sleep on your back and at first it may help to use nasal strips.
For more info go to the normal breathing website.
You may have an overproduction of histamine or histamine does not get broken down efficiently, so you may do a trial of MSM powder, max, 2 x 1 teaspoon daily.
Also if you have an upper respiratory track infection, magnesium chloride,
pharmaceutical grade 1oz per 1 liter of water sipped SLOWLY per 24H
is a constitutional remedy. If you drink it too fast it has laxative effects!!!
Please do you own research for the above suggestions, as my comments are not intended to replace medical advice.
Cheers.
Niko