I am sorry Abbie has this trouble.
It sounds like miliary dermatitis which is an allergic reaction. She could get it from being bitten by one flea that snuck in.
You can give her one quarter of a 4 mg chlortrimeton every 24 hours. It is a teeny pill so if you add it to a tablespoon of canned cat food, tuna or baby food chicken (no onion or garlic) she will not detect it:
You can use plain neosporen or raw honey on her sores. Both are safe to lick:
Now weight loss is another story and should be checked. At her age she could be hyperthyroid or diabetic.
If he has this ailment it can be treated with medication and a special food. It is made by hills and called Y/D. It comes in wet and dry forms:
Read about diabetes here:
Since she gets so stressed going out suggest calling a mobile vet that can come to your house to see her.
I can locate one for you if you send me your zip code.
Please let me know how Abbie is doing. Reply here or if you prefer we can speak on the phone.
Please be so kind as to rate my answer with positive feedback, as that is the only way I receive recognition from the site for my assistance. Thank you!
Providing a positive rating will not end our conversation, should you need me for any follow-up. Simply click 'Reply' for clarification or additional information, if needed and I will always be here for you and your kitties.