What Causes Severe Pain Below Sternum After Eating?

I have been experiencing intermittent abdominal pain below my sternum for about six weeks. It happens after I eat, especially breads or pastas, but it can happen with any food really. I have to eat small meals my stomach tells me when to stop. If I eat even one bite too many, I experience severe pain and then nausea/vomiting. The pain lasts for an hour or two after vomiting then slowly subsides. I have a history of GERD, but it has also gotten much worse over the last few weeks. I also have a gastric band that has no fluid in it. About a year after it was placed, it slipped and isn t in the proper place anymore. They removed all the fluid that was in it so there is very little restriction from it. I ve had it since 2010 and it hasn t been a problem since having the fluid removed in 2011.