i never thought the medical care in Texas was so bad :(
but still i think u need to be more persistent when u at the hospital with him : demand that they do cardiograms & ultrasound
and to speak with a cardiolog.
what u describe is a very negligent or unskilled med team. (or both)
maybe u can go to another hospital? don't give up, demand better treatment. (i've no idea how these things work there...maybe telling them if sthg. happens u will sue them?)