Over the past few days, I have started to experience an unusual skin irritation. It doesn't occur all the time, but mostly occurs when my shirt rubs against my abdomen, which causes a painful sensation. There is no visible sign of any rash, rednesss, etc. I use the same detergents to wash my clothes that I always have, and have made no changes to personal hygiene products, like deodorants or soaps, so I can't see it being an kind of allergic reaction.
The part that I found really strange is that there is nothing visible in the affected area, and if I lift the shirt, and try to re-create the sensation using my hands, including scratching it with my fingernails, it doesn't irritate my skin. Any ideas?