My male guinea pig (Toby) is around 3-5 weeks old. As of 1/13/18, he weighed 303 grams. Yesterday he dropped to 298 grams, and today he weighed 287. He is eating and drinking normally, and he saw a vet last week for an eye problem, and the vet didn't comment on his weight or point out any problems regarding weight. Is it normal for young guinea pigs to have dips in their weight? At what point should I be concerned about his weight loss? If it turns out to be serious, how can I help him put on weight?
His daily diet is abut 60% timothy hay, 30% veggies (red cabbage, romaine, bell pepper, celery leaves, occasional carrot), and 10% of a bland pellet (no fancy dyes or dried fruits )