Its called Dissociation and is extremely common with anxiety sufferers. Most of us here have felt the same way. But I do have a solution.
Stop being upset by it, or scared, or frustrated. Accept it is there and it will happen. By worrying so much about it, you are accidentally making it worse. You need to regard it as a temporary shift in perception, because that's what it is. By doing this it will have less power over you, and it won't last as long when it happens. Eventually, you'll just stop being upset by it all together, and it will pass before you know it.
This is easier said than done, obviously. But its the only way to make it stop. You are in the worst, earliest stages of this sensation. It gets better. And you can always come here to get reassurance if you need it.