Help, I’m getting bad at the motorcycle 🙂

Hello biker, I recently have the problem that driving is bad for me. It’s totally paradoxical. I have been riding motorbikes with sporty motorcycles for over 25 years. In recent years it has been a little less family-related, but I have been driving a little more often since last year. Now I have found out that on curvy routes, where I slow down a lot hard, put on the brakes, and re-accelerate, actually gets bad. As if you were a passenger in the car , who reads something on a curvy road and doesn’t look forward. Or as with some coaches on curvy roads. On normal highways, in the city or on the highway everything is good. But if there are smaller, curvy roads (e.g. in Taunus near Frankfurt or in the Odenwald), where there are many changes of direction and acceleration/brake phases, then the nausea starts. Is just corrosive because I have the feeling that I can’t handle my own moped any more. someone? Is this possible due to age (go to the middle of forty, but don’t want to believe it’s because of it)? Also think about letting me check through by a doctor.