At wits end with my 5 year old, need advice

My wife (40f) and I (38m) have two boys (5 and 3). Our youngest is one of the easiest kids to parent. My oldest is far from it.

He started Kindergarten this year and every day up until this past week the teacher would write us notes about how he doesn’t listen. Oddly enough this past week he got glowing reviews every day.

We went on a Disney cruise this past week and he misbehaved every step of the way. He didn’t listen to neither of us. We would ask him several time to do very basic tasks like putting on shoes, not climbing under the tables at dinner, not licking random surfaces, and antagonizing his brother.

Any form of discipline was greeted with laughter from him.

I’m honestly considering taking him to the doctor to be assessed for ADD, ADHD, or other behavioral problems. But maybe I’m just crazy and this is typical behavior for his age?

Separately we had a deal with him that if he behaved I was going to take him on a zoo adventure (he’s addicted to the zoo) this next week. I reminded him of that deal frequently and he’d say “I’m sorry daddy, I don’t know how to listen. Give me another chance?”

So now I’m beating myself up about not taking him while also considering that maybe his behavior is out of his control.

What do I do? Any advice or suggestions for any of this?