What Causes Loss Of Appetite And Abdominal Cramps In An Elderly Person?

my dad is 78 yrs old and just got out of the hospital last thursday. he had double pneumonia with Haemophilus Influenza as well. His lungs are also clear now. Here's the problem, the just fell on Sunday at 1:30 am and hit his head and hurt his back and abdomen. Before this fall, he was walking around on his own, with a good appetite for three meals. Now since the fall, he doesn't have an appetite ( won't eat hardly anything at all) and has abdomen cramps and back pains. Since the fall, he just had a 'very' small bowel movement and is having a hard time going to the bathroom since he's taking Percocet for pain. He's refusing to go to the ER and will need to be transported via Ambulance because he is unable to walk very far or get in a car. My question, is should he DEFINITELY go to the ER to be x-rayed and checked? I'm worried he could have some internal injuries from the fall and also, that he is on Coumadin as well.