Please help! Am I imagining a ringing sound or is it really tinnitus?

This question probably sounds really dumb but I'm really worried. I hear a very faint high pitched sound in my ear at night in my bedroom and can't decide if I'm imagining it or not. I've never been to a rock concert and never have music up loud, but I have a history of hypochonriasis and anxiety, often googling symptoms and thinking I've got certain diseases and conditions. I've researched tinnitus and it looks like a horrible lifelong condition, I'm so worried if got this. Sometimes the sound seems to go away and I only hear it at night. When I went into the bathroom I didn't think I could still hear it. I'm driving myself crazy and getting quite upset, am I imagining the sound? A few months ago I thought I was wheezing at night and went to the doctors thinking I'd got asthma but had full tests and all but I didn't have it. I know it sounds stupid but I have an anxiety problem and it's debilitating. Wish I could just relax. Any responses woulld be great thanks, thanks for your time.