bad rash

My daughter has a rash and it hurts her so bad when I wipe. I'm putting destin cream on it. Could it be a reaction to scrambled eggs ? Or is it the coke I've been drinking ? I only drink coke like every other day but yesterday I drank about 3. I breastfeed her. She's also had scrambled eggs for like the past 4 days. She's 7 months