A phantom neon light randomly appeared all over my map

Hello folks. Something absolutely bizarre to me is happening. Today after one of the rebuilds I did in my map, a mysterious light appeared all over. I hadn’t changed basically nothing other than placing a few lights and moving some BSP around. It’s bright blue and it seems to bounce all over. I proceeded to delete all the lights in my map, and start over. To my surprise, whenever I add any point lights, the neon light appears. It looks disgusting and I have no idea what it is.

Here’s a couple of pictures: Imgur: The magic of the Internet

For reference, the first pic is supposed to be quite dark with yellow lights, but turned to this.

Thanks in advance.