I really do need help!

I have been experiencing lags for the past 2 weeks and I only have 200pings, and it's not the lag where I get dc'd then reconnect back, it's like slowmotion moves, skills and others. Like when I go in team fight or hit minions it hits it but it doesn't show in the screen that it hits , but it only shows that I got goldafter the minion is dead. I cant figure what is the problem someone please help me.