I don't know where you live but I would never leave my dog tied up and unattended. Someone may have kicked her or teased her for all you know.
If it were me, I would only take the dog along to places she was allowed inside and leave her home when I did errands at places she wasn't allowed
Hey! I would figure that she is doing this out of fear. Dog's don't think "Oh, we're going here, but she'll be back!" It's more like, "I know this, I had a negative experience last time, I'm uncomfortable, I'm going to tell her."
You can do the strict way and use two fingers to "correct her" like Cesar Milan. If it helps, youtube some of his stuff. Watch his show. If you are afraid of your dog, the muzzle might be needed. He suggests not to do what he does without consulting a professional.
Your dog may also need more exercise. Do you have a treadmill? So you take her on really long walks? She is a terrier and terriers have more energy than the average dog. You need to fulfill every part of your dog to have a stable dog, you know?
If you want, and you would like to know more, feel free to send me a message. I'd love to see you're little ones fear turn around.