I rolled my ankle 5 days ago, now it feels much better because i can walk with little pain, but why is my foot becoming purple now? its been 6 days.

This is common: You break small blood vessels and what you are seeing is the color of the blood much like when someone has a black and blue mark. No worries, it goes away.

Ankle: The blood vessels that are injured in a sprain leak blood into the tissues that is broken down by enzymes in the body. Turning purple even 6 days later indicates the level of tissue damage . This is not a concern unless you are still having pain or mobility issues .