Fluker's Repti-Boost help

[Amateur Chameleon]

I have a juvenile male that has been refusing to eat or drink in the past couple of days. I bought repti-boost and tried it this morning and he wouldn't even open his mouth. How do I go about getting him to eat it. Because if he won't eat his food, he gets no calcium, which is bad.

I just need help on getting him to open his mouth.