There are a few things that cause hair loss on cat. I will discuss a few possible reasons for hair loss. First, it could be a flea allergy. In flea allergy, you cat has developed an allergic reaction to fleas. This causes over grooming. The best way to treat this is prevention. Prevent your cat from being exposed to fleas. Some cats develop infections or need a steroid injection to relieve the allergic reaction. I do recommend a vet visit for this condition to ensure your cat does not have a skin infection. Until then, applying a flea control such a frontline or advantage will help prevent flea from continuously infecting her.
Another possibility is hair loss to an allergy that your cat inhaled, such as pollen, or to her food. Generally, we start to see allergies develop in cats around 3-5 years old. Because you did move to a new area 5 months ago, it is possible that your cat is now being exposed to an allergen that she was not exposed to at the old location. Once again, cats can develop skin infections from over grooming due to allergies, so she should see the vet to ensure she does not have a skin infection.
Another possibility is a fungal infection called ringworm. Hair loss usually occurs in circular patterns around infected sites. Often, you will notice hair regrowth in old infected sites as the infection moves. It is happens to be ringworm, it will need to be treated by a vet. Be aware, ringworm is zoonotic meaning it can be transmitted to humans. If you start to notice circular lesions on you or other household members, seek doctor care.
Less common in cats are mites called demodex mange. These are mites that are common on dogs. The infect the hair follicles, causing hair to fall out. A skin scrapping by a veterinarian will determine if it is mites that are causing hair loss.
Another less common possibility is hyperthyroidism. Hyperthryoidism is when a cat's thyroid gland produces too much thyroid hormones. However, only 5% of hyperthyroidism cats develop symptoms before the age of 8. In addition there are other signs that are more common then hair loss in hyperthyroidism cats, such as weight loss. However, your veterinarian should inspect your cat for this possibility.
There are also many other less common medical reasons for hair loss. Here is a website which provides a nice list and detailed descriptions about possible medical reasons for hair loss in cats: Causes of Hair Loss in Cats
There is also another possibility. Sometimes, cats can start grooming due to a stress related change such as moving 5 months ago. This grooming behavior is a type of displacement behavior called feline psychogenic alopecia. To combat this problem, there are few things that need to be done. First is to see your veterinarian to ensure that it is not a medical reason for hair loss. Second, increase environmental stimulation, such as kitty toys. But you need to rotate these toy (So that they continue to provide stimulation). You should also engage in play periods or short training sessions (10-15 minutes daily) to help keep your cat focused. You will need to learn not to reinforce the bad behavior (the excessive grooming), and reinforce the good behavior (playing, cuddling, etc.). Two best forms of reinforcement are food and attention. In addition to this all, you should provide a hiding place, where he can retreat to if he needs. Third, speak with your veterinarian about using
anti-anxiety drugs to help control this behavior. Patience is needed. Sometimes, these behavioral problems can take weeks to months to correct depending on how much the behavior is ingrained in you cats personality.
I also understand that veterinarian bills have increased in the past few years. I have listed below are
several organizations that provide assistance in paying vet bills to qualifying people:American Animal Hospital Association
Angels 4 Animals
God's Creatures Ministry
The Pet Fund
United Animal Nations
I hope this helps and I hope your cat gets better.