Son with a Urostomy

I have a child almost 13 years old with a Urostomy. He has gone throuh so much over the years I won't go into detail but at this point we can't find a good pouching system Nothing stays on for more than a day. And since he devoped a skin irration I can't even get a full day sometimes changing it 2 or more times. He seems to also be allergic to the adhesive so we recently got samples from another company of stuff with a special backing. His ostomy is fairly new was done July 30 of this year. The problem we are having is the side of things are too big for his body and the ostomy was placed lower than the usual place. I don't know what to do we are working with Ostomy nurses and his doctors but I feel like we are getting no where. I hate to see him not wanting to even go to school because he knows he will have a accident in class and for his age it isn't easy.