Hi there, as I was playing with my guinea pigs today, I noticed Jack was not being his usual, curious but cautious self. He just runs away and jumps, almost like popcorning when there is a noise, any noise, and is desperate not to get caught. I have no other pets right now, so an animal cannot have frightened them. I also noticed Jack is gaining weight, and I'm certain he is a boy. Any answer would help! Thanks so much!