RABBIT HAS A DOUBLE CHIN

Question
Since the weather has turned very cold my rabbit seems to have her head close down, hunched into her neck, it looks as though she has a double chin now as she has a bulge of skin under her chin.  I  bring her into the house every day for a run round but she still has the bulge under her chin.  She has more than doubled in size in six months.  I got her in June when she was 8 weeks old. Thank you

Answer
Your rabbit is a female, so this roll you are describing is what is called her Dewlap. This is what the female pulls fur from when she is building her nest. No matter what you do to exercise her, this will not go away. That would be like removing one of your legs, it is a kinda body part that develops with age on most breeds of female rabbits.
Samantha