Weird keyboard issue

Having a bit of an odd issue with my keyboard. First off, it's a laptop keyboard, so replacing isn't exactly as easy as it could be (and costly, it's around $80 for a replacement for my laptop). It's a Lenovo G550 if that means anything.

What happens is that my ability to type certain letters goes in and out. Sometimes it will work great for some time, and then it will stop letting me type certain letters. When it stops letting me type those letters it usually last a few minutes, then I can type them again just fine. The amount of time it goes out varies, sometimes it's just a short time, sometimes it's so long that I have to go and copy paste the letters to finish typing something.

Pressing and holding them does nothing, it just doesn't respond. It does this only with y, u, h, j, n and m as far as I can tell. Also sometimes when it does work, I end up with two of the letter when I typed one.

I have tried cleaning the keyboard, even removed the keys and cleaned under them with some rubbing alcohol. I have uninstalled and reinstalled the drivers as well. I have also checked settings for the keyboard, run malware and virus scans and run CCleaner and did windows updates. It did get better for a short time after that, but is back to being very annoying. In the midst of typing this it happened around five times now.

I haven't tried a USB keyboard yet, because I don't have a spare that works. I do have my old keyboard for the laptop, but haven't tried that yet because it has a broken I key and swapping is an immense pain in the butt. Not fully convinced it is the keyboard as well because it goes in and out.

Ideas?