I got my belly pierced 3 weeks ago, and my skin has darken a little around the pierce and one night I was sleeping facing down and when I woke up and I tried move it around it was hurting a little is this normal??

From my own experience with a navel piercing, the skin does bruise a little and gets very sensitive. I wouldn't think much of it, especially considering it is so fresh.

Sleeping face down causes your weight to press on that sensitive area, which can cause a good amount of soreness and make it very hard to move, but I think you are okay

If it starts to become ***** and forms some big scabs, then you should consider it infected, but this is just the healing process