In part, it depends on your state's licensing requirements. In some states, a psychologist may prescribe medication. I would hope that is an option explored much further down the line if necessary. A psychologist has more academic training, and some of this is in doing formal psychological testing to determine what is going on. Formal psych testing is not necessarily part of a counseling process unless the situation is unclear/complicated presentation of symptoms, etc.
I'm a clinically licensed SW in Kansas and a clinically trained clergy who used to work at the Menninger Clinic (now in Houston, own by Baylor). I agree with the comments about it is not about the letters. I think it is true that a parent should check out a professional to determine her/his sense of connection with the person. That doesn't necessarily mean it will work for your boy. Gender may or may not be important depending upon what the underlying issues are.
While I'm not Freudian in my approach, I don't think he got it all wrong (smiley face), and know this is an important time in the development for boys in relationship to their mothers. I say that to say this, gender may make a difference, and I don't know if he is more comfortable with one or another. He may not have had any male teachers or coaches of sports to allow you to have a feel for that, but if so ask.
I think getting suggestions from any number of sources may be helpful. I used to do clinical training of clergy (most of whom intended to be pastors). Part of what I encouraged them to learn was who are the best mental health referrals in your area, and to find out sooner as opposed to later once you get to a new town.
So, even if you aren't part of any congregation (church or temple), if you know a clergy with whom you have any connection, they are happy to be helpful. As the risk of offending some, it is generally the clergy from more "liberal" traditions who would have this information.
I would pay attention to how long someone has been in practice as well. Even if one is using psychological testing there often comes a point in which the professional makes a judgment as to whether she/he thinks this or that about someone's problems. Seasoned professions develop a "feel" for certain situations/issues what have you, and can be more adept in responding. Often, the quicker someone catches a feel for something, the sooner some sort of resolution or treatment can be had.
If you are at a point of thinking your boy needs help, I am sorry. I know it is painful to see your child suffer. What is so difficult with mental health issues - anxiety what have you, is that a child is often less able to put what is troubling them into words than an adult.
And, we adults always, always can clearly identify whatever is at the root of whatever is bothering us with pinpoint accuracy in every moment of time, right? Maybe not.
Sometimes I have to talk to think. I forgot about two other important avenues to explore:
1) Those trained and/or certified in child attachment theory. As many children's issues can be related to his/her sense of connection/disconnection with parents or other key people in their lives, it has to do with her/his sense of attachment. While most professional have training in this area, it is a relatively new focal point for care and treatment and a blossoming field with much research being done in it.
2) those certified or trained in child therapy. This is a relatively new field so some of the best most seasoned professionals may not have these credentials, but often the play therapy certifying organizations have lists of their folk and can tell you if anyone is nearby.
I wish you and your boy well.