Question My PC all of a sudden is getting 20 frames when I usually get 120.

[LourdeGourde]

I was playing Fortnite at my usual settings the day before and I had 120 avg FPS. But today and yesterday I have gotten a max of 120 but a min of 16 and I get random huge lag spikes. Samething with Borderlands 3 and any other game I play. And this occurs during the entire time I play. I checked my internet, the task manager, I uninstalled apps I didn't trust. I've tried everything I know to do. Can someone please help me with what my issue is.
PC Specs: i3-8100 (looking for an upgrade)
RAM: 16G
1TB SSD
250G Hard Drive & 2TB Hard Drive
GTX 1060 6GB
Motherboard: Asrock Z370 Pro4

 

[rgd1101]

cpu/gpu temp and usage during the game?
make and model of the psu?