Soreness of parastomal skin is not something to be tolerated. I had a similar problem the first few months. Finding the right pouch and learning to cut the flange oval to match the shape of the stoma helped. I routinely use calamine lotion, aroma powder, and a spray-on skin barrier. With that, I get 3 to 5 days between changes. If I begin to feel any irritation, I change the pouch the next morning. The soreness is caused by leakage under the paste or barrier ring.
It took a few months to get a routine that worked for me. Going to a convex pouch was a big help for me. Things will get better over time. I am now 15 months since my ileostomy.