Thanks for your query.Based on the facts that you have posted it appears that your husband who has undergone surgery of Renal transplant and pancreas
transplant has developed what is called as Incisional Hernia
due to weakness of the muscles of anterior abdominal wall.
The loose motions that he has now may be due to enteritis
(Bacterial infection in the Intestines)
Please consult qualified Gastro- enterologist for clinical evaluation and further treatment.
In the mean while give him more water and electrolytes to maintain his water and electrolyte balance.