Welcome to healthcare magic!
Your problem is really very complex. So many possible causes are there.
Two of your medicines need to be switched, Singulair
needs to be stoped you can take other inhalations anti-asthmatic which are equally effective, You are taking excessive doses of iron- I would suggest 100mg thrice a day after meals, which is most tolerated dose.
You might have post-surgical bands which result in intermittent obstruction and pain, that is more so a case if you are totally well in between the episodes.
Another prominent possibilities is tuberculosis
If your problem does not get resolved soon please review with your gastro-surgeon and possibly you would need an exploratory laparotomy
for a diagnosis and intraoperative intervention if possible.
You need a physical examination by your physician and get base line investigations like Chest X Ray, Electrocardiogram, Complete Blood Counts, Renal Function Test, Liver
Function Test, Fasting and Post-Prandial Blood Sugar, Thyroid
Profile, Lipid Profile
Abdomen, Urine Compete Examination.
This work up is expected to detect the underlying problem so a definite treatment could be started.
I hope this advise would be helpful for you.
Still if you have any queries or doubts, please write me back,
I would be happy to solve them.
Wish you a great health!