jacksons chameleon not eating

ok so ive had a jacksons for a while and it hasnt been eating. he is green as can be and super friendly and active. drinks plenty of water daily. what is there that i can do for my chameleon to get him to start eating again. im up for suggestions. i know its not that i dont have a variety of food. tried that.... ive even tried giving him liquid vitamin b12 in his water to enhance his appetite.... that worked for about a week but then he went back to not eating for another 2 weeks or more. he has been to a vet nothing about that helped any. im up for suggestions let me hear them

force to eat....or give food go away because he might be a little scare to eat in front of you

heyy how u post?