My puppy is limping!!! :(?

Alright, so I was holding my little pomeranian puppy last night, and she saw food and scrambled out of my arms. She does that alot so I tried to hold her and place her on her feet, but she flinched fast while she was in my lap and started yelping really loudly. Once she stopped, she was limping and putting no weight on her back foot. After she calmed down, I moved all of her joints around from her hip to her hock to her foot. She didn't whine or yelp or even flinch. If anything it was her hock. When she walks around, she will walk with her foot with a slight, barely noticable limp, but when she gets up from a nap, she holds it up and stands with only 3 legs. There is no swelling at all. Does this sound serious?