Why would I feel nauseous when I touch the inside of my belly button?

Inspired by rooeytoo’s question about flossing and nose-itching, I was just wondering about this because ever since I was little, touching my belly button has caused me to feel slight nausea and I can’t do it for very long otherwise it feels quite unpleasant, almost like I’m going to throw up.

Does this happen to anyone else or is it just me? Could it just be a nerve in a weird place?

I never thought much about it until I shared it once on the internet a year or two ago and people acted like I was a certifiable nut…lol