Maybe because I took Ritalin twice yesterday but I had really bad dizziness today. Really bad. And it got worse in the middle of the day so on my way back home from the annual physical I avoided the busy highway. Just did not feel safe driving on it. It took me a while getting back home using other less busy routes. Then I took a nap and still was dizzy after the nap, but soon afterwards the dizziness sort of lifted abruptly and the rest of the evening was just fine.

I will avoid taking two pills of Ritalin. I have read on Reddit that dizziness on Ritalin is common and is a dose-dependent adverse effect.