Worried for my Children's Physical and Mental Health

I'm in an inter-state custody situation with two young children and I'm not sure who to contact. It's been about 7 months since the custody agreement went into effect, and in that time, BOTH of my children seem to constantly be sick. Both seem to be having constant Respiratory issues, one has developed asthma, they seem to constantly be losing weight, and one has has chronic ear infections. They both cry and beg me not to make them go home and I hear them crying Loudly as the drive away. Since I am the non-custodial parent, I dont know what my rights are or who I should contact. If Anyone can help me, Please tell me. It kills me to see them sick and unable to play every time I have them and so upset every time they have to leave.