The main treatment in conditions associated with child psychology are psychotherapy, cognitive behavioral therapy, interpersonal therapy, speech therapy and medications. In ADHD, stimulants are prescribed along with structuring child's school environment. If a child is suffering form depression then along with psychotherapy anti depressants are added. Other medicines too might be added.

There will be problems in multiple areas like with family, relationships, academics, friendships. A child requiring psycotherapy will show signs and symptoms like
he will withdraw from family, friends
prefere to stay alone
negative behaviour
anger
tantrums
self harms
negative talks
hopelessnes
will prefer to stay aloof

You can consult a psychologist and a pediatrician who is specialized in treating special children to help diagnose and manage the condition, if you suspect your child has a psychological condition.

A child psychologist will not be able to prescribe medications but can provide detailed psychotherapy. One will need to consult a psychiatrist to prescribe medications as they along with psychotherapy together help in managing the mental conditions in a child.

Yes, speech therapy is a part of child psychology treatment as it helps build language, social interaction skills, helps in building relationships and assisting in language development and vocabulary.