Today I was scratching our pot-bellied pig while she was flopped over on her side, and she began trembling. It was quite pronounced! My husband said he's seen her do this before. (He spends a lot more time with her than I do, since she lives in his workshop. ) I was concerned. Is this normal? (When I stopped scratching her, she got up and stopped trembling. She appears to be eating, drinking, and otherwise acting normally.) P.S. She is 11 months old, has not been spayed, is somewhat overweight , has never had any health problems that we know of!