Hi My Name Is Janet Sandoval And I Am An

Hi my name is janet sandoval and i am an owner of a yorkshier terrier. He is about 2 years old and very energetic. This morning he started acting very different starting from the point that he didn't want to get out of the bed. He tried to bite my sister every time she tried to get near him which was very odd of him. When we offered him a treat he wouldn't take it either. When we finally managed to pick him up he started crying in pain. I believe its his arm but nothing seems swollen or injured. When we get near him he cries as if we hurt him. Can you please help me on what is going on?