I updated my email on SO, and for some reason now, I've lost 4 silver badges and 10 bronze badges. Not sure what is going on here, does anyone have an idea?
Your account history shows that the email change caused your account to be automatically merged into an older one. This causes all badges from the newer account (which got merged) to cease to exist. If you still qualify for them, they will be automatically awarded to you again whenever the respective badge processes run next. Many of them have already been given back to you, but some will take a while. Noteably tag badges, which are only awarded when the tag scores are updated at 03:00 UTC.