I have a small yellow line under my skin leading to a red spot above what is this?

Skin doctor can help. Uncommon skin rashes, unusual spots, or interesting lines are hard to describe in words. A dermatologist (skin doctor) would have to look at it, maybe under a magnifying glass, and decide on a diagnosis. A primary care doctor can also help, especially if one has other bodily symptoms at the same time as the skin symptom.