Welcome to Healing Well! I'm sure it's very disconcerting to have a new pain. I have had three endoscopies and like yours, biopsies were taken. (It's routine.) I have never experienced that type of pain as a result of any of my endoscopies.
I know the sore throat is a pretty common immediate symptom, although I never experienced it. I have never heard of stomach pain post endoscopy, although perhaps someone will be by to say they did. I've been around this forum for about four years, so have read many post-endoscopy stories.
Hopefully you'll hear from other members soon.
Glad you've joined us!