Many people break out with a rash
from fiberglas. I suggest you have the
headliner replaced as soon as possible or face continuing problems.
For the itching on your skin, you need to take a shower in this manner. Start with a comfortable water temperature, and turn it colder little by little. Let it get as cold as you can tolerate it. Use soap and cloth sponge or another bath aid. to completely wash your body.
The glass will exit your skin and you'll feel better soon.