“Why is my tongue blue?”

My name is Ashley and I am 13 years old. This morning I woke up with a blue tongue, it looked like I ate a lollipop or something. I searched it up and it says that a blue tongue means that there is a lack of oxygen in my blood and I should see a doctor right away. I'm concerned so are there any others reasons on why my tongue would be blue? I didn't eat anything that was dyed or colored.