Dell xps 15 9550 built-in screen (1920x1080) messed up after using usb-c

Hello,

So recently I got myself a brand new external monitor to use with my Dell xps 15 9550, I used a USB-c to displayport to connect it. The first week it worked fine but after that my built-in screen got messed up. Now by messed up I mean the screen gets lines of colour all over it, as well as it is flickering. This issue solved itself at some point but it only lasted a couple days before happening again and I haven't gotten it to fix since. I have a feeling it's a software issue but everything is up to date, does anyone have a fix for this? For an issue to occur then go away is strange, I know the issue is the USB-c to displayport but, in this case I'm just looking for a screen fix and I'll avoid the USB-c until there's a work around.