Tortoise makes screeching sound.- Please help

by Vanessa
(Culver City, Ca)

I have a 1 1/2 year old tortoise who is indoors and not hibernating. He has a heat pad and a basking light. He just started making this screeching sound like 2 months ago. I have 3 other tortoises, this is the only one I've ever heard this noise from. It's a high pitched and sounds almost like it's replacing the normal hissing sound they make. It sounds like "EEEEH". It was startling at first and weird but didn't think much of it. But, now it's more often, 7 times a day, that I hear. My first concern was upper respiratory disease, but his nose looks dry, nostrils open, and no bubbling. Appetite is less but being that's it's winter I expect it. I can't find any info online. If my turtle is a screamer, fine whatever but, I just don't want it to be something else like respiratory problems, obstruction, or anything else that can affect his health. He also opens his mouth a lot around the time he is screeching- which makes me think it might be some kind of obstruction. I've searched online for this but no luck. Please help.