It’s such a difficult situation many mums find themselves in, including myself with DS2. I can empathise OP it’s awful and very upsetting to go though.
The best advice I can give is to work with the school, they need to know. what is your child finding difficult, keeping up with work, have they fallen out with friends, being bullied etc. or just that they do not like the school system and that is causing the anxiety. Has your child been assessed for dyslexia? I know finding a educational psychologist at LA level isn’t always available. We paid for private assessment, it was expensive though, (£400 10years ago).
My DS2 is dyslexic he didn’t like school at all, knew every trick in the book to stay home, or leave school etc, just to give you some hope, my son left with one GCSE, that was a minor miracle as we didn’t think he would pass any. He now works in a niche area of tech, he has a great work ethic and is doing really well, he was a changed person once he left school and started to work in an area that was interesting to him.
Good luck today, I hope you get your child to school and school will listen & can help your child to feel a bit more settled. Take one day at a time. Sending hugs.