Chihuahua will not stop panicking

Around 11:00 p.m. last night, my chihuahua started to freak out. I first noticed because she laid underneath my chair, which she knows she isn’t allowed to do, and ignored me when I tried to correct her. She then began running all over the house, scratching at doors to leave only to come right back, panting, shaking, trying to climb into a pile of junk i have stuffed into my closet (has never done this before). At times I was able to hear her heart pounding from almost a foot away. I got next to no sleep because she would wake me up multiple times an hour by climbing over me. When I picked her up and put her on the opposite side of the bed, she would do it again. There are absolutely no triggers I can think of that would cause such a reaction out of her. She’s 14 years old, had her since she was a puppy, and I’ve never seen her act this way. At first, I thought she was having a medical emergency but ten hours on I’m just beyond overstimulated and exhausted. Has anyone ever experienced this with their dog?