Big lump under LO's eye?!

Robyn

In the bottom picture, you can see the eye is swollen. It doesn't seem to hurt him at all and is only slightly red. To the touch, I feel a lump under the skin. My son had very bad baby acne when he was little so I'm not sure if it's just a pimple that is under the skin OR something more serious. He woke up with this yesterday morning and it's still there!

I'm worried! Any advice?