After the Kellogs memory mission my game started to make flashes and now everything has a negative effect to it. It's like when you go on a camera and set it in negative mode. That is how my game looks like now. Please do help if you can. Thanks.

Disable Wetness in the game's launcher. If your problem is indeed what I think it is, this is a rain-related bug on (mostly or exclusively) AMD cards - the aforementioned solution should make your problem disappear.

I forgot to mention I play it on Xbox one..... Sorry thanks for the help anyways!

Ouch, nevermind then. Is your problem https://www.youtube.com/watch?v=gBHUlXFvo5I? Have you tried restarting the game / fast-travelling elsewhere after the quest / reloading a previous save to see if the issue is still present?