Sever Lag or Personal Lag?

For the past two games I have had ping of 42-48 consecutively never going above 70 ms, but for some reason I am lagging. I have several seconds where i cannot move, change attacks, or use spells. Is this something on my side or is something going on with the LoL server that is making me lag like this?

P.S. I played yesterday with no lag at all.