SEN teaching assistant wanting advice on diet/fluid refusal

SEN teaching assistant wanting advice

i work as a sen teaching assistant with a lot of autistic children , there is a huge diversity in the levels of need in the school. I get help and training, and i have experience as well. But i am also keen to do some of my own research on some issue that come up.

a concern i have it with one child who is 9 , pre verbal and very aggressive and hyperactive. He absolutely refuses to drink any fluids, (we use pics to communicate) not only this but he refuses even slightly wet food (sauce, gravy , yoghurt, jelly , ice cream etc) he has no issue physically witb eating or drinking as he used to do it . His family don’t speak english so its hard to discuss issues with them, i have reported it to the principle to follow up. He mostly will only eat crisps and dry chicken. I think dehydration could also increase his hyperactivity. 

Has anyone else had an issue like this?