Babies aren't for everyone.

I babysit my niece whenever her mom goes to work. They also live with us so it makes it easier for me to keep an eye on my niece throughout the day (meaning like causally keeping an eye on when she eats/sleeps/gets teething meds and what not so when it's time for me to babysit I already know what schedule she's on.) 

Today at noon someone pointed out that my niece was poopy. Of course I assume that her mom changed her after I left the room. Baby takes a nap and wakes up, plays for a little then I come to babysit so her mom can leave. I notice she smells again so I go to change her. Her diaper is filled with so much pee it's almost leaking which happens when she naps, but she had been up for an hour already so she shouldn't have had a full diaper like that. Then I realize all the poop is dry and stick to her butt like it's been there a while. She has a huge rash all over everything that her diaper covers which wasn't there this morning. I have no 'proof' but I'm almost 100% positive she let the baby sit in poop and sleep in it for almost 5 hours. I'm so mad. She does stuff like this all the time.! It's so frustrating. The baby is in pain her diaper rash is that bad.