I need help getting information to gain custody of my son, or legal visitation. I do pay child support, but I am not receiving any help from them. I fear my son is living in an unsafe environment. I have approached his mother with the idea, but since then she has changed phone numbers three times and I have not been able to consistently talk to my son. I usually get him for holidays and summers but I fear now she will not allow it. We live in different states as well. I really am lost please if anyone has any information that can be used, I am open to all suggestions thank you.

It begins with your divorce decree, or separation agreement, if you were married. If you were not, you will need to petition the court where they live for visitation or custody. This is why there are lawyers, so get a referral for the best one in that community.
Check this: Child Visitation: Frustration of Visitation Rights/Non-payment of Child Support Child Visitation Rig | DoItYourself.com

Go to your local family court and inquire. Probably better if you go to an attorney.