gud morning doctor

i have a problem related to upper abdomin pain after taking food. feeling very less apetite, continously weight loss, low blood pressure, initially gall bladder operated due to stone, last year 8.5 mm stone detected in uretor, since last 10 years taking throxine for thyroid. presently whenever i eat something pain started at upper abdomen just below the chest in right side. please advise me what to do or i go to which doctor for consult.