Hi welcome to HCm 
I have gone thru  your query regarding 
severe asthma  .I can understand your concern .
Dear, Any health problem you face does not happen  all of a sudden but is outcome of your faulty life style and food habits for long time and thus weakened immune system .
Although many people with asthma rely on medications to prevent and relieve symptoms, you can do several things on your own to maintain your health and lessen the possibility of asthma attacks by detoxifying by  following diet control and increasing activity level -
yoga ,pranayam -deep breathing ,
meditation  . Regular exercise can strengthen your heart and lungs, which helps relieve asthma symptoms .
 Eating plenty of fruits and vegetables may increase lung function and reduce asthma symptoms. These foods as ginger ,garlic , turmeric powder ,  and black pepper ,long pepper  are rich in protective nutrients (antioxidants) that boost the immune system .
You have to shun alergens from your diet as very oily food or dairy product or ice cream which you feel, give you problem . Over eating is always bad .
 Ayurvedic  Kunjal with warm Salt water -drink 4-6 glasses and vomit  every off and on , detoxifies your system , gives strength to lungs and all vital parts leads to ultimate health .
Avoid 
constipation , 
sleeplessness ,
stress ,tea ,coffee , 
smoking ,alcohol
water intake is very essential .
  It is advised to see your doctor for further guidance .
Hope this helps solves your query .Take care , All the best .Wish Get well soon .
Don't hesitate to get back tf have any further query .