Hello Vicki Partial bowel obstructions can be detected with x-ray abdominal series. It will show an enlarged (distended) bowel and air/fluid accumulation above the partial obstruction. Further testing can be done with a small bowel follow through. You drink the white barium and the radiologist will follow it through your small bowel by x-ray. The time it takes and the pictures can tell.
Your other symptoms sound all too familiar: bloating (from air and stomach contents), cramping pain (from bowel trying to move contents forward and not being able to), vomiting (it's got to go somewhere) and Diarrhea (from bile salts and enzymes which are still being produced by your digestive system). When you have an episode, you should have an x-ray done at the ER to be sure your not totaly blocked and possibly get a tube in to empty your stomach and let your bowels rest.
Hope this helps. Take care Eva