Yes my son has anxiety everyday on way to school and vomiting when time to go to doctor or dentist. We work through it social stories and calming techniques help him.

Wow @LauraColumbo! You telling your daughters story reminded me about how my now 20yr old daughter did the exact same thing in 1st grade! Funny thing is she doesn’t remember it...(hell, I forgot!) Had to go through the same “mental counter game” to teach her to stay in school. She had early morning gym and would complain of feeling sick or getting hurt during dodgeball (has anybody ever really thought how sadistic that game REALLY IS?!?! I was pretty physical of a kid and I hated that game!).
Love the “cast-iron stomach” comment @A MyAutismTeam Member!!
LOL!

The first sign that anxiety is ramping up in my daughter is "throwing up." I put it in quotes, because she doesn't actually throw up, she just heaves over a bowl. She gets herself so stressed out that her stomach is literally in knots, and she starts feeling sick.
When she was little (1st grade), she REFUSED to get on the bus to go to school. I would drive her to school, and then I would have to leave when she was not looking, her anxiety was so great that she would stand in the classroom and cry. We finally got her on the bus, and she figured out that if she threw up, the nurse would send her home. So she threw up on the bus. Every. Day. So we called in the Principal to talk to her, and we agreed that the bus driver would hand her the trash can when she got on the bus, and if she threw up, she HAD to stay AT SCHOOL. The school nurse threw a fit because if a child vomits, protocol is that they get sent home. So we had to convince her that my daughter was deliberately getting sick because she wanted to go home. By the end of first grade, I was never so happy that school was finally done.
Now my daughter is 19, and she made it through the next 11 years of school, but I know when she grabs a bowl and sits on the couch with a miserable look on her face, the stress level is unbearable for her.

My son throws up at the dentist every time. He does not like doctors, especially not touching his mouth.

Yep throughout toddler years and even today if too worked up. E is getting better at managing her emotions but that has taken a while.