@luckytran

I would like to recommend Wim Hof's breathing technique to anyone suffering from sickness, particularly lung related. It has done a lot for me personally as a lifelong sufferer of asthma and allergies.

I understand if people have their doubts, but the cost of trying out a new breathing technique is quite cheap. You can learn it for free online, and practice whenever you want.

I hope someone finds this useful. I wish you all the best.