Constantly scared of someone breaking into the house

I still live with my parents as I am a teen. But for the past few days, I've been rushing inside when I've been looking in the care for something, or going into the garage to do the laundry by myself. I freak out and I'm always terrifyed I'm going to see someone with a gun, trying to break in. The other day I was looking for my charger in the car. I was just about to open the door, when I suddenly was positive that someone would pop out of nowhere from inside the car and scare me. It's weird. I've never been this scared of nothing before. Every time I go outside by myself when no one else is around, I'm just terrified. I start sweating and my heart beats faster and the only thing I want to do is run back into the house. Once or twice I think I was almost shaking, while I was doing laundry. I don't have anxiety or anything, at least I don't think. I've never been tested for it or anything. Is this just like me being freaked out, or is it something a bit more serious? Thanks ^^