All public schools have psychologists employed by their district. They can observe the children and make suggestions to the parents. If they are not a trained Diagnostician they can't really make a diagnosis. But a Psychiatrist or Developmental Pediatrician can. We had our 3 year old grandson evaluated for Autism and other sensory disabilities as soon as he turned 3 and it was through the public school system, free. They came and observed him during his class time at Mothers-Day-Out. He had started acting out and it was obvious something was not right.
They observed him over the period of several weeks and came back with a plan to help him. He didn't qualify for the special needs class for 3 year olds at that time. The changes they suggested worked very well to keep him calm and more focused. The Director moved him from the 2-3 year old class to the 3-4 year old class and it was night and day. He did marvelous in the older classroom.
At Head Start this past year he has not done very well and the school Psychologist is making sure he gets in a Pre-K classroom with the public school. He can be evaluated and observed over the period of the year and they can make suggestions and requests through out the year this way.
Call a Children's hospital in your state and find out what services they might offer in the way of evaluating and testing.
I have a friend who now lives in Billings MT that did some training and could evaluate for learning disabilities. She did it for people and did not charge because she just wanted to help kids learn.
Your friend can also make an appointment with an Eye (glasses) doc that can evaluate for eye/brain disabilities. They can basically retrain the brain in how it receives information and processes it. They use glasses similar to those used by Nicholas Cages character in National Treasure where they flip different colored lenses and read a particular worksheet. They also have exercises they do to strengthen weak areas. My grandson was nearly blind in one eye due to not having glasses, his brain had stopped processing the information that eye was sending it. He did exercises with the odd glasses and he can see perfectly now with corrective lenses, his brain is processing the information very well now.
There are many ways a parent can go about this. Getting help earlier is better than latter.