Needing help and advice on my sons support at school!

Hi all, my son is 5 still awaiting diagnosis. His school has been non compliant for the past year. When he was in Nursery a support plan was set up. This was updated when he went into Reception last year and they put support in place as this is when his refusals to go to school happened and they progressed throughout the year. He was having 3 sensory therapy sessions daily, help with toileting, speech and language therapy etc. They started decreasing his sensory sessions & 2 weeks before the summer holidays this year he was off school due to meltdowns, anxiety and sleep difficulties relating to school. Through the summer holidays his headteacher made promises that the support plan would stay in place and they would review in the first couple of weeks of him starting Year 1. We where even promised that we could view the SEN classroom they have with only 6-8 pupils as this is what we feel and know our son will need due to his difficulties with groups of people in the same room etc. When he started Year 1 in September his support plan has basically went out the window, they stopped sensory sessions, my son has been coming home with dirty underwear and told us he went the toilet by himself, this is a massive concern as he still struggles with this and it clearly shows this when he is coming home with dirty underwear. He has told us other kids scare him as they scream and run after him and he has to hide. He says he is not allowed to wear his ear defenders in class, which is a huge concern as any sort of noise can cause him distress. The teacher told me he has pinched children and hit a child in the face with his bag because they laughed. After several communications about our concerns we put in for an EHC assessment, the school cancelled this as they say academically my son is fine and is exceeding academically. I have seeked advice and spoke to SENDIAS and other support agencies including this website and thought I would try and come to some sort of agreement with the school to put support in place. The headteacher has now stated in an email to me that in his opinion because my son is doing well academically he probably shouldn’t be on the SEN register and he probably does not have SEN. This has made me feel physically sick and me and my partner of 15 years are confused on what to do next. Our son has been on the SEN register for some time now but when ever I spoke about funding to the school they kept coming back and saying they don’t get funding for our son. And now the headteacher said he will be contacting SEND to ask them if our son should still be on SEN. We are afraid to send our son back to school as he will hold things together and lash out at certain times in school (school don’t see this as a concern) and massive meltdowns at home. May I also add I have reports from physiotherapy and his paediatrician stating that he has no awareness of danger and needed 1:1 supervision from an adult to keep him safe. He also has hypermobility in hips, ankles and feet. Flat foot (which we are awaiting special shoes or insoles for shoes from Orthotics). Any advice would be greatly appreciated.