I Have A Small Bump Under The Skin On My

I have a small bump under the skin on my right eyebrow near the peak. It SOMETIMES hurts when I touch it, others I could push on it and no real pain. It has changed shape and hardness a couple times. It seems more flat now but in a bigger area. Think a gum bubble that deflated, same area size, but different shape. As far as I can tell there is no outward discoloration or other sign that it's even there. What could it be?