My son is 3 doesn't speak has these episodes like a tantrum but they appear out of no where and for no reason having him tested for autism but what co?

Child psychiatrist: You should take him to the office of a skilled child psychiatrist to clarify why this happens. Sometimes it is not a severe condition like autism, but other (easy to correct) factors, like siblings dynamics, general health issues, environmental exposure, etc, might be the cause. Get him examined, your pediatrician may guide you.

Have the evaluation: By a specialty team (developmental/ behavioral pediatrician, child (neuro)psychologist, speech/language therapist, occupational therapist et al) & call your public school district's child find team for assessment for early childhood special education services. Unprovoked tantrums, characteristic of autistic spectrum disorder, are treated by intensive behavioral intervention at your son's age.