Hi.
Thanks for your query.
Noted the history and understood your concerns:
Being 43 kg at the age of 32 is underweight; although I can understand that you are asthmatic.
Since you are asthmatic, you must be taking lots of medications including bronchodilators, steroid and so on for such a long time and all of them can really be causing
gastritis,
duodenitis,
esophagitis with GERD, ulcer and so on.
This needs to be diagnosed by an upper GI Endoscopy after preparation with bronchodilators, nebulization.
The pain in the back and chest indicates esophagitis either as a direct effect of the medications or due to GERD that is
gastroesophageal reflux disease.
Till then try to get a relief with the puffs that is inhalers and try avoid oral medications.
Get started with a PPI like
Omeprazole.
Antacids every three hours, particularly when you are on empty stomach.
Soft bland diet.
Rest of the medications as per the clinical evaluation, examination and reports of investigations.
Also get an opinion of a Pulmonologist to get the review about asthma, get the proper medications adjusted for the need but at the same time stomach friendly.