POLL : Why did the Doctor did this 2 me??/?

I wentt for a check-up for a bleeding elbow, yet he said that he will check my entire body , and he did that after that he told me Close your eyes, I want to insert a thermometer in your mouth, I closed my eyes and he inserted something big in mouth, IT WAS THICK and hard and I do not know what it was, what was it guys? I hope it was thermometer. I am scared, will i Get aids by thermometer??