Is withholding medical care considered child abuse?

My son’s mother and I have shared custody of him. Over the last year my son has started acting out in school and at home. He is aggressive and can’t focus on anything. His pediatrician recommended that he get tested for ADHD and wanted to prescribe him some medication to see if it would help. He also recommended our son get counseling before these issues get worse. His mother refuses to consider any of this. She believes the doctor and I just want to medicate our son so he’s easier to control. Is her refusal to follow the doctor’s recommendations and allow medication for our son considered child abuse? If it is I want to pursue charges against her and get my son the help he needs. If it is not, is her refusal enough for me to gain full custody so I can make these decision for him and not be blocked by her?