Hi - you're doing the right thing in requesting a referral + speech therapy is also v important so hopefully your ST will know about autism, if you're sure that's going to be his diagnosis in time. Advice about helping him: despite him not being diagnosed you can relate to him as if he has been diagnosed. You can check out loads of info via the home page + put things into practice. You can observe whether he's got any sensory issues : reactions to smell, taste, touch, noise, textures etc which may be causing him difficulties. There's also loads of info via the posts. If you do decide to do this, then you really can't learn everything at once, so concentrate on how his as yet undiagnosed autism affects him as an individual because it does vary. I don't know if you can stop the regression, however much you want to, but you can support him. Most communication is non-verbal so you can do him a daily timetable consisting of pics + point them out to him + say the words. Keep it as simple as poss. This way he can see how his day will be - routine is important. Does he understand single words, short phrases? Then keep on using them + demonstrate practically what you mean. Such as holding a beaker + saying drink. That sort of thing. I appreciate you need to go through the diagnostic process but if you're really sure he's autistic then it makes sense to proceed from that premise + relate to him in that way. Good luck.