I experience heavy laggs without ping jumps

I constantly experience heavy lags, while having normal ping, around 30-50 ms in general, but it doesnt jump up when the lags happen, so its definitely not my ping. I get rubberbanded back to locations I've been seconds ago, sometimes my champion just stops and then seconds later all the abilities I pressed during that time get casted. Sometimes its just stopping without response. It's really annoying, and I've caused many problems in my games, by just walking in and not being able to do anything, or just stopping and getting caught.

Is there anyone who's experiencing the same? Could it be a server problem? I need help because I dont know if I could play again, because I cant trust my ping!