How come my acne scar from over a year is red and feels bumpy what can cause this?

Infection: You should see a Dermatologist for best answer. You probably have a low grade infection, which may require systemic antibiotics

Inflammation: Something is irritating this scar, either infection or persistent inflammation. A very effective photofacial, the BBL by Sciton, can relieve both conditions, even without antibiotics.

Scar, keloid: It could be a form of scar that is called a keloid , where it gets carried away by itself and over grows. I would suggest a dermatologist to examine it.

See doctor: it could be an infection,inflammation or thickened scar tissue.