I also received a 1099-K from Paypal as I live in Mass and made $1,500 on personal items sold at a loss through ebay. I found the answer to my question here:
https://www.mass.gov/service-details/frequently-asked-questions-about-1099-k-notices-from-third-part...
This tells us all we need to know about about what we need to do.
It sounds like you will need to do nothing if you were selling personal items at a loss.
Good luck!
