Pretty much what everybody else has said. + Congrats on losing the 3 lbs.!
Unless your Facebook friends are qualified professionals who've conferred with you personally about the nature of your pain, then there's really no reason to give a lot of weight to their advice/criticism, since they're speaking from a position of ignorance.
One possible good thing from this is that it gives you the opportunity to think about how you might handle this sort of criticism without feeling bad or working against yourself (the pizza) in the future if/when you run into it again.
You're doing great!