There's a device called the Otolith [0] that supposedly can cure vertigo and supposedly prevented motion sickness in VR, but they're only chasing the market for solving vertigo.
Curiously, what games are you playing? I find that games that involve real world motion didn't match virtual world motion (ie, any racing or flying game), I feel sick within seconds, but games where the two worlds always match (ie, Beat Saber, Pokerstars VR, Superhot VR, Space Pirate Trainer), I could play for literally HOURS and feel fine.
Games where I'm sitting down like a car, I wouldnt get motion sickness, but the ones where you walk around with the keypad like Medal Of Honor and Half Life Alyx are the ones that I cant do anymore. I was having a blast with medal of honor, playing 30-45 minute bursts until the nausea once set in very bad and stayed since then.
I dont get any motion sickness from room scale games (real world motion match virtual world) like ping pong or watching movies.
As far as I can remember I've always been sick in cars, when I'm not driving. When I first tried my Q3 headset, I couldn't stand it for more than 10mn in a row. The trick I discovered works for me, but I wouldn't bet on it for everyone else. I removed my shoes and I play barefoot, with my two feet firmly on the ground. I couldn't play Population One until I applied this trick.
Now after many months of using it, I must say I feel pretty confortable. My main usage now is watching movies or videos on cinema size screen.
Curiously, what games are you playing? I find that games that involve real world motion didn't match virtual world motion (ie, any racing or flying game), I feel sick within seconds, but games where the two worlds always match (ie, Beat Saber, Pokerstars VR, Superhot VR, Space Pirate Trainer), I could play for literally HOURS and feel fine.
[0] https://otolithlabs.com/nvrt-technology/