Weird thing happening to me recently. I keep forgetting basic things I've done thousands of times before. For example, I was doing some electronics and needed to do solve a linear equation with two unknowns and I forgot how to simplify the equation. I just couldn't remember how to do it. I had to go check a textbook to remember. I've done these type of problems thousands of times over my life. Another example is that I suddenly forgot the pin code for my phone, even though I have used it thousands and thousands of times without even thinking because I'm memorised so well. What the fuck is going on?