My 6 month has a jitters or shakes for like 3 seconds or 4. 6 to 7 times a day maybe more.he don't cry he is calm. could this be seizures?

Could be: Infants sometimes have twitching type movements but seizure activity should be ruled out. Take some videos of your infant's activities and show them to your infant's doctor. He will probably want to see the infant.

See doctor asap: children your child's age who experience brief jitters or generalized shakes may be experiencing seizures. You should have your child seen by your doctor and have an electroencephalogram to help diagnose the problem.