Some researchers claim that any gains in weight experienced by subjects using GH alone was due to growth of internal organs and connective tissue, which could cause some problems......if true. Most studies do not agree with this theory and consider "GH gut" to be a myth.
I do know of a few guys who were allergic in some way to synthetic somatropin, and had various ill effects.
It may be something else entirely.....a lot of the things I use cause intestinal discomfort from time to time. Phase out one item at a time and see what hapens.
GH is very short-lived in the body, so stopping to see wouldn't be any big deal. Creatine, glutamine, protein products, orals.....all can fuck with your bowels, as you know. Hell, dirty gear will do this.