upset stomach vomiting no appitite

I am 32 yrs old and have 2 kids 14 and 10. During the past 3 yrs I have lost 120lbs I have no appitite and will start
vomiting and feel sick alot. It is usually in the am and after I eat. My stomach swells and have extreme pain. I have been to the emergency room approx 1 every 2 months for dehydration but I havent gotten any reason why its happening to me, they took an x-ray and showed nothing but thats all. My vitamins are low even with taking alot of supplements(vitamins). When Im hungry and go to eat, I have 2 mouthfulls and feel so sick I cant put food in my mouth or ill vomitt right there on the spot. Im so sick and tired of this due to the fact that I lost so much weight my skin hangs face, legs,arms and the worst would be my stomach. I would love to have that removed but i need to know and have treated whatever is doing this to me because I cant stop losing weight? I have the diarrhea alot(mucus). but I have it for 2-3 days and dont go to the bathroom againg for 4-5days on normal but I have gone over a week or two without going at all but no  constipation pains.  I cant lose anymore weight it looks bad and im tired and cold all the time. I live in Canada and was wondering what test should i have done?

[B_Shel20]

I would have an endoscopy and colonoscopy to check both ends of the GI tract. This will help by either finding the problem or eliminating other diagnosis. The endoscopy for sure, as it sounds like an upper GI issue. If both of those check out clear, look to doing a capsule endoscopy.
Your case really needs serious attention. Get to a GI specialists as soon as you can.