Should I Repeat Brain Imaging Should Be Done?

Question: Hi, my father had a bad fall nearly 3 weeks ago, as hit his head on concrete and had s seizure, he was taken to the ED. He has heart & kidney disease which he has managed ok.
Now he has been in hospital for nearly 3 weeks and every day his mental and physical health has drastically declined to the point where he isn’t eating, vomits if he does eat, low level of consciousness (only answering yes/no and not being able to hold a conversations), very dizzy - he can’t even sit on his bed, must be lying down, his arm trembles if trying to lift anything light, cannot breathe well (oxygen in mid 80’s if not on oxygen). The dr is hoping he improves when his heart valve is fixed (waiting for surgery) although his blood pressure/heart is currently beating normally. Any ideas on what is causing this daily mental and physical decline? He also had a very painful ache on his neck which after a day travelled down to his right inner arm (the pain has now stopped and he is on blood thinners)
Note they did a CT scan when he was first admitted and everything looked fine - this was nearly 3 weeks ago, should they do another? Or different imaging to detect bleeds?
I’m scared the hospital has missed something.