My dog is 11 years old she is a cross breed a pom and a yorkie?

last night while i was out she was at home with my son he said she had some kind of fit twice she began to shakeing ,gasping for breath and her head lolled back once or twice she also appeared to be weak like her back legs were not working, when i got in the fit seemed to have ped she was lying on the couch and seem happy to see me her heart when i put my hand on her chest was racing fast i lifted her down and she was able to walk even though she was shaking still but not very much she had a small bit of food and some water she then stayed in her basket ,this morning she is as right as rain although when i touch her i can still feel a small shake ...would she have had a heart attack ?? she is in good health and not over weight at all in fact she is very fit and agile..