Bypass Surgery impact

hi friends,
My father had bypass surgery 2 months ago. He is take care him self properly and followed all the advise given by the doctor. He is 63 years old, non diabetic, just controlled BP.
He went for the first follow up few days back and the x-ray his heart n informed that there is some fluid build up around his heart n give medicine to make it come through urine.

after few days... my father experience pain on the rib side and having short of breath, we were afraid that something will happen to him and we rush him to the hospital. now he is admitted to the ward, they suspect there is some water and pus and also clot blood inside his stomach.    

this required a small operation to take out the thing that i mention above, according to them...
my question is ...... is this one of the side effect that some of the bypass patient will experience....??????

I cant see my father suffering like this. His face is showing that he is holding to much of pain inside him becoz of this problem. plz anyone give some supporting words,,,