Chanice,
Thanks for the post.
Firstly, seeking care from emergency room physicians for a non-emergency is a good way to get poor care. If you are worried in the middle of the night about a new cough, fever, or whatever -- fine, take your father to the ER. But you need to follow-up the next day with his primary doctor. ER physicians are not well-suited, or trained, to take care or more sub-acute problems in someone with your father's extensive history.
If you and your sister are concerned, it is probably with good reason. Seek attention from your father's internist. "Fluid on the lungs" can mean many things: pneumonia, heart failure, pleurisy, etc. An internist can help you sort through this illness.
Good luck.
I don't want to be an alarmist but I also want my father treated correctly and I am not convinced this is happening at the moment as his own GP/Doctor is telling him to take heart tablets in the morning and then other doctors are saying it is evening. Who do you believe.