I have a couple of ideas for you that I hope will help. Here is the website for the Wound, Ostomy and Continence Nursing Society:
You may also want to try contacting the Oley Foundation:
Oley's focus is on enteral and parenteral nutrition (tube feeding) but just as with colostomy and ileostomy, gastrostomy and jejunostomy procedures can require the assistance of stoma nurses for proper healing and care, so they may be able to guide you in the direction of Ostomy Nurses. Oley is a very well-known, extremely "connected" organization in the GI community and they have extensive resources for patients and clinicians.