Bag problems

My mum has had a bag for a few months now, and she's just started chemotherapy about 3 months ago. Whenever she goes through a treatment the wounds around the stoma open. Often it becomes quiet large and it bleeds a little bit, she is also on a blood thinner. I've taken to taping the bag down so the edges seal, but we're at our wits end.

Any ideas on healing the wound or at least keeping the bag down so nothing leaks?
Also, she has been having an acid like discharge, would this be the cause of citrus fruits, etc?