Boo boo booty :(

Sami has the worst case of diaper rash I have ever seen!!! OMG it's horrible! Her little bum and entire diaper area is so red. She was fine yesterday morning and then I put her down for a nap and about an hour into it Patches snuck into her room and woke her...ugh.
So Sami woke screaming and I went in to get her and she was inconsolable. I thought at first that Patches had startled her and she was scared and that's why she was screaming and crying so bad...then I thought maybe she has a head ache...I know sometimes when I wake up suddenly I get a really bad head ache. I tried everything. She was literally crawling up my body and screaming and I could not calm her down. I brought her into our room and held her on our bed and tried to cuddle with her and hold her. She would climb all over me I would try and give her her space (since she's not a clingy baby to begin with) she would crawl over to me and rest her head on me and try and catch her breath. I could tell she was still tired but just so upset.
I layed down next to her and she climbed on top of me and nestled her face in my neck and finally fell asleep for a bit (about 15 minutes, maybe)
She woke again still upset and crying. I smelled that she needed a diaper and changed her. She was red, but it didn't seem that bad. I cleaned her up and held her some more. She sat on my lap and stared at me totally expressionless for about 20 minutes. My heart ached for her. Something wasn't right. I thought maybe it was her teeth. I kept feeling in her mouth for molars or anything pressing through but there was nothing.
We went downstairs and I gave her some Tylen0l, to help with the teething or headache or whatever it was that was giving her so much pain.
I sat her in the high chair and I started to try and think of what was wrong. she was clenching her legs when I held her and wouldn't sit on my hip when I carried her downstairs. She would curl her legs up and hold them there.
While she was in her high chair eating her snack she burst into tears and started screaming twice, but only for a few seconds. I again thought maybe it was teeth.

After her snack I changed her again and realized what it was. She had peed and her diaper area was so raw that when she peed in her high chair it was burning her.
In just a few minutes it had gone from a little red to raw burning red. I was horrified. I loaded her up with some diaper cream.
Later that night it became redder and was wet all on the surface. I wiped/blotted and dried her and it was wet again..it was RAW skin and very painful.
I put some medicine on her before bed that I had from a rash when she was a newborn and she slept through the night and woke up with a smile.
When I changed her morning diaper I could see she was drying up and healing but now there were blisters. OMG.
This poor girl. She seems much better today and is not in as much pain but it still looks incredibly painful!
It's definitely healing and getting better but if this redness doesn't go down by tomorrow afternoon we will be headed to the Dr.
Thank God she's at least not in any pain anymore! I just don't understand how this happened. She was fine one minute and horrible the next. It's unbelievable how fast this rash came on.

Poor baby booty :(