Hello, My name isXXXXX will try and help you as best as I can.
When did this all begin?
Has you hedgehog had any bloodwork done? The fact that she has petechiae is concerning. She definitely needs bloodwork to check if she is anemic or has a low platelet count. This can be as simple as a drop of blood on a slide or a full computerized blood count. Petechiae are due to a platelet issue, either a low count or a problem with platelet clotting. Even if your vet does not have a lot of experience with hedgehogs, bloodwork is relatively straightforward and easy to interpret.
If no answer is found on the bloodwork, x-rays of the chest or an ultrasound of the belly is warranted.
This would be to look for changes in any of the organs that might indicate a source of the problem.
Thank you for the advice. She passed on at 4:30 am.
She passed away before you responded.