Huge bald patch under chin and on chest

Question
She was 1 year old when we got her and her previous owner said she had her spayed. I don't know the person so I can't say this is a for sure but she is now 2 years old and nothing like this has happened before neither has she been near any male rabbit. She doesn't appear to be itching the area or scratching at it but I have seen her pulling the hair out during grooming. I just don't know how to get her to stop or why it started in such a short time. One day she is fine the next she is half naked on her front.  I just want to help her and I have no idea what to do.
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-----Question-----
Hi I have a 2 year old dwarf bunny that is very well acclimated to our home and family but this evening we noticed for the first time she had a huge bald square right down the center of her chest and on her throat area! I almost had a heart attack! It even looks like she pulled on her hair or bit herself hard enough to bruise herself. She is in a spacious cage at night and has the run of the house during the day, her cage is always clean and she always has fresh veggies, hay, pellets and water and wood to chew. WHAT is going on with her? Should I be worried? What do I do for her?
-----Answer-----
It sounds like she either is or thinks she is pregnant and is plucking out fur to make a nest. However, that would be the case only if the bald areas are where she can reach them.

If they are high up on her throat, it is something else causing it. If that is the case, she may have fur mites or (less likely, but not impossible) skin allergies. She may have pulled out hair while biting and scratching to try to relieve the itch they cause.

Going back to the first idea, if she has been anywhere near a male, including if a male was outside of her cage (rabbits have been known to mate through the wire of a cage), assume she is pregnant. Otherwise, she may just be having a false pregnancy where her hormones are going crazy and are making her think she is pregnant. Getting her spayed will stop it from happening again, and it will also bring a lot of other benefits such as removing any chance of uterine or ovarian cancer, which can help her live a lot longer and healthier life.

Answer
Does it appear that she is eating the fur? Sometimes rabbits with dietary deficiencies will start pulling out and eating their fur. I've found this happens more often in long-haired breeds, but it is not unheard of in other breeds. You might want to take her into a vet to get a blood test done to determine if she is having nutritional problems. These are not  overly uncommon in rabbits as they get older.

If she is spayed and does not have mites to cause her to bite or scratch at her fur to relieve itching, that would be the most likely cause.