Like Mom2MrQ, I have similar sensitivities to chalk. Just the thought of touching it gives me the "nails on a chalkboard" feeling. I also don't like being barefoot on concrete -- somehow it's very similar in feeling to the chalk.

I'm not sure whether it's OEs though, so I guess I'm not much help. DS9 has many sensory issues with texture, some that are more related to sound than feel. He hates the sound of twill pants rubbing together; he only likes heavy sheets because the sound the soft ones make is like fingernails on a chalkboard. He's HG(+?) (DYS) and has other issues that seem like OEs to me but I haven't done enough research to say that for certain.