New Laptop crawling to its death?!

Hello everyone!

I have no idea where to put this issue under in the forum since I do not know the exact problem, I apologize.

I am using my phone atm to type this. If there are any formatting problems with the text, pls disregard it.

** Pc: dell Intel inspiron 15 5548

Processor: i5 5200U 2.2GHz

RAM: 8GB

64BIT Windows 8.1 (switched to windows 10 after purchase)

** Problem: my laptop I bought during summer break (August 2015) is showing a constant 100% disk usage. It would dip to random values between 0% - 100% when its idle. When u launch an app like chrome, then it shoots up to 99%-100%. Opening a folder or anything causes the same reaction.

Most importantly, boot time has become sluggish!

** Solutions tried:

-'high performance' on power settings

-disabled super fetch service

-disabled BITS service

-disabled Windows Search service

-ran cmd and typed in chkdsk.exe /f /r (took all night)

-disk defragment for disk optimization

[Noticed no difference, at this point I thought windows 10 was the problem with all the ninja updates.]

-reset my pc to factory settings (wipe everything and back to windows 8)

[I really don't think any thing is wrong with the hardware.]

-tried dell diagnostics on boot and everything came clean

-nothing is corrupted that alerts my attention

[I don't think I have been struck with a virus.]

** Things I've downloaded:

-malwarebytes free

-cccleaner free

-Microsoft office from my school

-windows update (the handful important updates that I carefully picked out)

-this is my treasured work pc but I did have Steam and LoL when I had it on windows 10 (didn't play much though)

** Thought the drivers needed some fixing

-updated dell BIOS and graphics drivers (only things that were outstanding on their scan & download website that I did not have)

-performed full clean boot

-performed safe mode (I had my jaw open here when I noticed that it was still happening in safe mode. I have been forsaken by the mighty safe mode)

The laptop is functioning. However it has become VERY SLOW. It happens on and off. I used to be able to run photoshop but now I am barely able to access my notes. I'm scared of having to buy another laptop since I'm probably not able to afford another (tight budget for school at the moment).

I am desperate and I am asking if you can share your expertise on this issue. Most of what I did was recommended by other people in several forums to people who have similar problem to mine. I am not that tech-savvy.

I can post any media file you want to see (screenshots, videos, logs).

Thanks for reading all this. I appreciate all the help I can receive!

** My next plan is:

-Reformat pc to windows 7 (kind of doubting this will work since I have already downgraded from windows 10 to windows 8 and noticed no change)

-I read somewhere about disabling the WiFi and uninstall/reinstall the WiFi driver (however I think this is replicated in safe mode and that didn't work so...)