I feel like a bad mom.

Last night I had just changed my younger sons poopy diaper. Not even 5 minutes later my older son says "mom he still smells" and I was busy doing other things and said "I just changed him and it was really bad so maybe it's just his pants that still kind of smell like it" and they both continued playing. 30 minutes later my husband gets home, picks him up, smells him, and says "shooey you did a stinky" and changes him. Our sons butt was so red and hurt him so bad he was screaming. The poop was all over his privates and everything. My husband said "you didn't smell him? You didn't think to check?" I said I changed a poopy earlier and our oldest said he stunk but I thought it was just the smell lingering on his pants. I didn't think he'd poop again 5 minutes after I changed him. I felt horrible. I should have checked him. I hadn't felt very good all day (I'm 6 months pregnant and on partial bed rest Bc I'm considered a potential "high risk" since my babies come early and I have had placenta issues) I needed to get stuff done and was more concerned with getting my oldest's bed sheets dried and my husbands work clothes cleaned and dinner made that I neglected my poor baby's bottom and he hurt Bc of me and my selfishness... My husband gave him a bath to help clean his butt and make it less red, while I was so upset with myself I was crying and crying so hard I kept throwing up in the other bathroom. I just feel like such a bad mom. I should have taken the time to check his butt again.