Same with this guy getting anxiety symptoms out of the blue.
I can't diagnose him, so I am not saying he even has anxiety. However, when people get concerned that a health problem exists they over-analyze every twitch, ouch, burning sensation, dizziness etc. searching for clues to a mystery ailment. If you search this board you will find many threads started by someone with all or most of the "symptoms" your hubby has, but the difference is they were diagnosed with no problem, so YOU can tell their symptoms" are non-events, even though it i not possible for many of THEM to accept that diagnosis - the symptoms seem so real!
Since he hasn't been diagnosed, all I can say is sometimes they are right but usually it is just something they used to experience but they ignored it because they felt it wasn't important and would go away.
The fact the "symptoms" only occur during car trips makes it likely they are nothing important and can actually be happening at other times in the day but are not noticed. If concerned, check it out with doc.
Many people have headaches and nausea. The nausea can lead to problems so if it persists I would get that looked at though.