You can go to a doctor, either in his cabinet or in the hospital. It is up to him to make a diagnosis and eventually recognize a disability. It is only after this recognition that you can receive an allowance or other social assistance.
In the French Community, you can also rely on a medical-social worker (TMS) of the ONE. He/she can provide support to parents facing the disability of their child, knowledge of child development and knowledge of the psycho-medico-social network according to needs and demands.
In the Flemish community, a medical social worker of Kind & Gezin can provide you with similar services.