CS count jumping up and down

I just wanted to know if anyone else has been experiencing this issue. In game (along with match history) my CS has been jumping up and down. For example I have just played a game with gangplank. In this game my CS count would be 341 one second then revert back to 200 the next, then jump back up. I have a picture of my CS count being 341 (can be provided on request) then in match history it is back to 308. I will look into this further.