Feeling like a failure as a mom 😔

I don't know what it is, maybe I'm sleep deprived, but my baby could be crying or fussing and I'm just rocking him trying to get him to calm down and then my hubby would say "oh I think his stomach hurts" and only then I realize that, yes it does but before my hubby says that nothing comes into my head. I don't realize what exactly could be wrong with my baby. Why do I suck so bad?? I should know what's going on with my baby. 😓