When you suspect your child might have ADHD, it is always recommended that you take her to see someone who specializes in attention deficit disorder.
While I fully support this, you really need to be careful of one potential problem:

They might just be looking for ADHD.

One of the biggest problems with seeing a specialist in any particular field is that the individual might be too close to their own work to see your child's behavior as anything else.
This is particularly true of a disorder like ADHD that is so complex in presentation that it mimics many other possible disorders and medical diagnoses.
Just be careful.

Find out what you can about the person you are seeing in advance.

Do they diagnose everyone they see as having ADHD?

What other illnesses or disorders do they end up diagnosing?

What's their reputation, not only among their peers, but among other parents?

In many cases, you will do very well seeing a specialist.
Most experts in ADHD will know the signs and symptoms of the disorder, as well as knowing what questions to ask about the rest of your child's life and functioning.
They will understand the very subtle, and lesser known differences among the many possible disorders that can be diagnosed.
In fact, one well-known psychologist insists that all of his patients receive a thorough medical evaluation either prior to or as part of his ADHD evaluation.
"Why," you ask? Many medical illnesses or problems can mimic the symptoms of ADHD, and it is far too easy to overlook them and misdiagnose someone as having ADHD.