My 6 yr old was diagnosed with pdd-nos adhd odd tics anxiety and expressive and receptive language disorder how do i deal with the melt downs?

Beyond diagnosis: Even more important than diagnosis is the treatment. You asked the most important question - and whoever gave you the long list of diagnoses need to also provide a treatment plan. You have to be informed, understand the treatment plan, which includes behavioral interventions that deal with the melt downs. Please schedule regular sessions with the person who gave you the diagnoses.

Combination approach: Programs for management would include medications such as stimulants and Amantadine, clonidine for the tics and anxiety and consult with a behavioral psychologist. A consultation with a speech and language therapist may help with the language difficulties.