A.O.
A similar thing happened to my daughter at 8 months I was really concerned as well but I think it was because she was beginning to use her shoulder muscles to crawl around and pull herself up onto her feet to stand. I think her muscles were sore and she was just starting to discover that she even had shoulder muscles. At her 9 month checkup, the Dr checked to make sure that she didn't break her collarbone and said that she didn't see anything that worried her. The spasms only lasted for a week or two and it hasn't happened since.