Abdominal cramping pain, trouble having bowel movement, nausea after eating some foods and pimple like rash on buttocks... what's going on?

Henoch schonlein?: Look at images of henoch-schonlein purpura and see if that's wha u mean by "pimple" rash... Also do you have any joint pain? Either way, the symptoms are worrisome and should be evaluated.

OBSTRUCTION? : Intestinal obstruction is suspected when you develop abdominal cramping, nausea and vomiting, obstipation and constipation or inability to pass stools without flatus.