Pressure relief pillow disability (Horsham)

Hello everyone , My son who is 6 suffers from diagnosed hypermobility ( terrible pains in joints due to hyper flexibility ) he is on waiting list for physiotherapy and occupational health and it took us more than a year to get there … so I would like to help him feel comfortable … his back , legs , neck hurt constantly … I would like a pillow that I saw older people use it’s a foam filled pillow square and it is covered in plastic . But if you have any other ideas or équipements to help while we eventually get to see someone from physiotherapy I would appreciate . Thanks