Wouldn't worry to much-worms are easily treated and eradicated
I'm sure he'll be just fine, some of our girls like to eat little and often and as long as he's got the option of biccies and his water-he really will be fine, plus if you remove his wet food as soon as you realise he's not gonna eat it and leave it a little longer than usual before you offer him some more-he'll either let you know he's hungry or he'll adapt and eat when it's their-if it's one thing true of all cats it's they do not let themselves go hungry when they know they can have food
He's still in the process of training you
Also it may not be worms, it could just be that his tummy is growing with his intake of food-as he maybe wasn't used to having this much food at his disposal before