[mixingman]

My father is 77 yrs old,48Kg 162cm,living S. Korea and he had artificial heart valve 12yrs ago.
After that, he has taken warfarin and persatin, but about 1month ago,
he got severe abdominal pain, and blood stool,went ER,first, there is some kind of clump in the small intestine, but 5days later, it disappered, so he was out of hospital about 1week later,
But recently, he felt the same abdominal pain and went back to ER.and doctors found the same kind of clump in the small intestine.
I think that is cuz of warfarin overdose,( he is taking 5mg,and the next day taking 6mg of warfarin) because, while he is in the hospital
he stopped to taking warfarin,then the clump is disappered before.
Is my guess correct? is that one kind of side effect of warfarin?
then, how much does he take warfarin in a day? What PT/INR range is good for my father?
I saw some PT/INR home test machines, Is it ok to check PT at home? and those machines are reliable?

Please, someone answer my questions!!!!