Baby not wanting to eat

I pump and bottle feed mostly because he has a hard time nursing and then started to reject nursing. Now he’s rejecting a bottle. He acts like he’s hungry but then arches his back and cries and won’t drink. Maybe it’s reflux? I’m not eating anything new to upset him. He only wants his dummy. We have to bait and switch his dummy for a bottle.

The past two days he’s had about 500mls a day. He has an appointment tomorrow. Anything I should bring up or ask about?