Gastroparesis & bowel dysmotility for 2.5 years. yellow watery diarrhoea for first time. is this part of condition, or something else?

Gastroparesis: Most likely all related . Need medicine to treat this. Follow up with your doctor

Not likley: gastroparesis alone does not cause diarrhea. Some medications used to treat gastroparesis however can. Watery diarrhea is usually due to a viral infection(up to 2 weeks), exposure to antibiotics and if prolonged to a bacterial cause. Abdominal pain, bleeding and fever indicate that you should see a physician and have additional testing. Some motility disorders like IBS may cause diarrhea as well.