My guinea pig is extremely picky, is this normal? He will NOT eat any kinds of peppers, green beans ,apples (any fruits really) or celery and sometimes it's even a fight trying to get him to eat carrots. He has no problem eating Timothy hay, he loves the stuff. And it seems like the only veggies I can actually get him to eat is kale, curly parsley, and romaine lettuce hearts. Any suggestions?