In this area of the US a social worker is commonly thought of as someone who can help locate and access services in a community; one who works as a case manager for an entity like CPS or a school district or hospital, etc.
I'm not sure how a social worker could help with-difficult child's particular problem, but in either case I'd interview before starting with a psychologist or SW.
I don't know how accurate it is, but I found the following at
http://www.medhunters.com/articles/dearCPSwVsPsyc.html :
Dear Joyce♦:
What's the difference between a social worker and a psychologist?
Sincerely,
Wondering
Dear Wondering:
To answer your question, we contacted a social worker who is a hospital administrator at a teaching hospital. Here's how she explains the difference:
The scope of practice is different, but there is overlap in that both clinical psychologists and clinical social workers do assessment and counseling. Practically speaking, both do individual, marital, and family counseling. Both have credentialing bodies with standards of practice and ethical codes.
Social workers may also work in community development, advocacy, and policy development. Psychologists can have specialized areas such as neuro, where, for example, they would set up programs in and/or consult in behavioral programs for acquired brain injury, or autism, or for testing for learning disabilities in adults and children, or for testing individuals prior to surgery for epilepsy, etc.
Only psychologists can diagnose and interpret standardized testing. Also, the education is different: Psychologists have PhDs and psychological associates have Master's degrees. Social workers have a BSW or MSW a doctoral level of study is mostly for those involved in teaching and research.