Oh sweetie, I am so so so sorry. My heart breaks for you. Please don't think you've done anything wrong....it was obvious you were a wonderful beardie mommy. Yoshi had a fantastic life with you and knew he was loved.
I understand how fast they can take a turn for the worse, that's exactly what happened with Whiskers, it was a shock when he died too.
You're in my thoughts and prayers.
It's very hard dealing with it when it happens this way. I remember thinking Redrock would get better, especially when she improved on the day after we finally got to get her to a vet, the next day she was dead by 11am. I know you will always miss yoshi. I'm very sorry and I send hugs and sympathy your way.
It's heartbreaking when these helpless babies pass away. Even though we've been the best mom's we can be for them, it's taken out of our control. I know you're hurting terribly right now and I'm so sorry. All of us here grieve with you.