I need help determining the cause of dark circles? I am 20. They seem to have just popped up. None of my family has them (Photo)

I have an iron deficiency, so I take iron pills, but I don't think it's helping. I recently gained weight only on one side of my back, but I got my weight back down, though back weight is still there. Don't know if they are related but those are the only two major changes. I get 8 hours of sleep so I don't think sleep is the issue. Can you tell me what colors you think they are? I think they are a purplish blue, but any color you think they are would be greatly appreciated (photo below) Thanks!!

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