I've read your other threads. I think you need to google your Consultant's name, so you can find out what he/she is. If necessary ask for a referral to a specific paed - look up on your hospital website who has a special interest in development/autism/neurodisability.
In the meantime, compile a list of 'problems'. Break it down into sections - development i.e. fine/gross motor, communication, i.e speech/understanding, behaviour, sensory i.e. any issues with sounds, textures, smells, etc., sleep. Try to give examples.
Hopefully, you will be able to identify your DS's main issues, and get the help you need.
WRT sleep, there are a few causes. It isn't uncommon to have sleep issues, but managing them is a combination of minimising sensory overload and creating a safe sleep environment. Melatonin is helpful if the issue is getting to sleep. It isn't great for night waking.