csgo low fps ONLY in CSGO

[LOWFPS]

I have Ryzen 7 1700x 3.5ghz, single 16gb ram, gtx 1060 6gb, 1TB HDD, 250gb SSD, Alienware aw2518hf(No fps difference between 144hz 240hz).

Since 2 weeks ago, my fps drop 260 to 90, 3 days later, I have 150 fps, and finaly 60 fps drop to 30. My res is 4:3 stretched 1024x768, high settings ( fps doesn't change). I have no idea why my fps is so low. every other games working fine 90fps on PUBG with 144hz, 110 fps in RB6 with 240hz. I changed nvidia settings, game settings, launch options, but it's not working pls help me