Developed saggittal crainalsynostosis, pressure sensation, constant pain, breathing issues. What is the cause?

Hi my name is Caroline...my son is an x premi...born at 28 weeks.....was in good condition when born....and only ventilated for a few hours.....when he was 2mths old I was due to take him home but he developed saggittal crainalsynostosis and became very unwell over the nxt few months and the hospital wouldn't operate but in the end they had no choice as his brain was under severe pressure and he was having constant pains in his head.....after the operation he started to cry funny it was like he couldn't breath and cry at the same time....his operation was last November and no he has strider breathing he is 13 months corrected....cant walk talk crawl sit roll over he has no mobility of any kind im wondering what this is from......sorry about the long msg.