Why does one of my eyes have an extra crease/saggy eyelid? (Photo)

I woke up one morning with an extra crease on my eyelid. It is just on one eye . I have tried different creams but nothing helps and it just keeps getting worse! I am only 20 years old. I feel that the eye is usually more tired than the other. I do notice that it gets worse on days that I may not have gotten enough sleep. It feels almost heavy. It really bothers me and I hate how it looks :( is there anything I can do about this?