They will let you breast feed, they will put like a seatbelt around her, that is attached to your seatbelt. SO she can easily lie and feed and still be secure. The feeding will make it better for her ears to pop.

At that age there is not much to give medicine wise, I always use demazin on my boys, the GP suggested it cause they have ear problems. We also fess them before we fly, you can do that at 4 months, it is just saline nose spray and this clears out the passages a bit so they don't get stuffed up.