Hi, lrandall55! I have had a colostomy since September of 2015. "Pancaking" has been an issue for me on and off, and it is typically when I've drank too much caffeine and not enough water. And, all that stool collecting there at the top and definitely lead to the barrier pulling away with peristalsis of your stoma (when it is moving in and out--"active"). It helps if you wear an "extended wear" barrier as well. My stoma does not stick out very far from my skin, so when peristalsis happens and my stool is more solid, the pancaking happens. Are you still having to eat foods with low fiber (low residue)? Stay as hydrated as you can, and limit dehydrating beverages. Also, as others have said, make an appointment with the ostomy nurse where you had your surgery, as they are a wealth of information for whether or not you will do better with a convex barrier.
I personally get in the shower to change my bag. I use an adhesive remover spray and saturate my barrier prior to peeling it off. I use the spray as I'm removing the barrier. Wash your skin and stoma with a gentle, non-moisturizing soap and rinse very well. I dab my stoma gently to dry it, and then aim my blow dryer at the stoma and surrounding skin on a warm air setting. It will dry very quickly this way! Then, I apply a barrier protective wipe or spray. Hit it with a short burst from the blow dryer. If the barrier you use has hydrocolloid in it (it will swell when it gets wet), your sores (unless uber weepy) should heal without too much trouble. At least that is how it has been for me. My sores look like small raised bumps, and they are nearly always from stool leakage. I am blessed to have only had to deal with a yeast infection once with my ostomy. It healed quickly with stoma powder and an oral once-and-done antifungal medicine.
Once you've got your new barrier and bag on, take a warm heating pad (I have a small one that is microwaveable) and press it against your ostomy ring for a few minutes. Some people have told me that using lubricant and leaving a small amount of air in their bag really helps them with the pancaking. Let us know how it goes!