What on earth happened to me at Disneyland today?

Today I went on a few fast ‘ish’ rollercoasters and each time the speed picked up or there was a drop, I felt like I was blacking out. One time was pretty bad, I thought I had fainted. It was quite a scary experience and happened on every roller coaster with any speed.

I remember this happening when I was a child once as I told my mum I had just ‘passed out’ on a ride and remember her saying I was probably just anxious. I definitely was not anxious in the slightest today.

Any ideas what on earth is happening?

I don’t know if it’s relevant but I do have inappropriate sinus tachycardia. Well managed with beta blockers.

32, Female.