Banana! He probably loves the taste, ha.
Just my opinion--
I wouldn't keep him out of his home longer than you absolutely have to. He is probably stressed enough with the oral meds.
What I did with my boy when he needed a 14-day oral antibiotic was take him out when I needed to medicate him, put him back in immediately, and try to convince him to drink with a spray/shower (though if he was too stressed out, I would just continue to run the dripper).
After the 14 days, I would start building your relationship again with hand feeding/etc. To avoid the stress now.
Also, it's not a great idea to squirt water into his mouth afterwards. From what I have read, it is very easy to accidentally drown a chameleon this way.