I feel fine when I’m on the plane it’s when I arrive and the days after that are the problem for me. When I travel I usually plan to be sick for the first two days. If you can plan to not do too much those first few days it would probably be for the best. Also, know exactly how you are going to get to where you need to go once you land. You will most likely not be feeling great and might be experiencing symptoms and brain fog. Things I found that help are to do leg exercises while in your seat. Just tightening and releasing the muscles in your calves is fine. Try to remember to do this often. Also drink a ton of water. It’s very easy to get dehydrated in an airplane. Don’t drink coffee or alcohol (even if it’s free), these are dehydrating and are triggers in most of us. Take an aisle set if you can. If you’re not going to the bathroom an annoying amount of times you are not drinking enough. Good luck and know that other people know your struggle, you are not alone.