The stitch is on the inside of my ankle and my heel swelled up and its blue in color and very painful. What do I do?

See doctor. If you have angrier suture and have a blue painful area it is an emergency and you should be seen immediately. It could be a number of acute problems which need to be evaluated and treated.
See your surgeon. As soon as possible.
When was it put in? Need to know why the stitch was placed around the ankle in the first place. Was there an injury that was repaired? In that case the most likely cause is that the bleeding from that injury has travelled downhill from your ankle and made it bluish colored, the pain would be because of swelling most likely. But what I need to know is if you have had surgery, why, other medical conditions you have.