Dyslalia is the medical term, which means articular disorder i.e. inability to pronounce words or speak properly. It is a symptom and not a diagnosis. There are many causes of dyslalia such as (a) impaired hearing, (b) structural abnormality of the speech organs, (c) mental inadequacy, (d) learning disability. Before any treatment is started a diagnosis must be made and one should consult a good ENT speech expert.
Omega 3 are fatty acids. There is no scientific evidence that Omega 3 can help patients of speech problems.