I'm a deaf rider and use sign language. Have dealt with periodic episodes of vertigo dizziness since I was 23 (I'm 36 now) with varying degrees of frequency & duration. As someone mentioned, severe spins while feeling hot and vomiting are the worst.
Mine can come any time, but I can keep things in check by being careful with caffeine, avoiding fast food, managing stress, giving myself plenty of outs, and most importantly, alcohol. When I quit drinking & got sober 7 years ago, I was amazed how my vertigo immediately dropped to almost nothing. Don't waste your time around negative people or situations. Treat yourself well & congratulate yourself for any small minor good things you do.
Part of it could be psychological, as getting sober allowed me to deal with a bunch of inner issues, and thereby reducing overall stress levels from knowing I wasn't hitting the bottle to avoid other problems. On the other hand, I wasn't dealing with hangovers, and a lot of alcohol does involve grain hops (gluten source?) as I was mostly a beer & mixed drinks guy, not a wine person.
While I got sober for myself, I have to admit the huge reduction in vertigo definitely helped me stay sober in my early sobriety. Hey, if that's a blessing in disguise, I'll take it!
Obviously, I don't ride if I have the spins. However, I've taken plenty of long trips (12K avg/yr) and know myself enough to plan routes that give me flexibility if vertigo hits me, and make sure I give myself plenty of time for rest if I start feeling iffy. I keep meclizine & ativan handy, and take as needed, but usually don't need it while riding.
No shame in keeping a credit card handy & checking into a motel earlier than planned while on the road. I haven't camped while on the foad yet, curious how that will work out. Just having mental "outs" actually takes the edge off and lets me focus on the riding, including an awesome FL-CA-FL ride over 17 days on the FJR last Xmas.
Good luck to everyone! Just do the next right thing after the next right thing, and eventually the tide shifts back in your favor.
"When the going gets weird, the weird turn pro." -Hunter S. Thompson
Now: '06 DL1000, '01 R1150GS
Then: '06 FJR '01 FZ1 '07 DL650 '73 CB350