13 year old female cat licking & losing hair

Question
Hi & thank you, we were able to get a product called "Zodiac" similar to Advantage but much cheaper at the local pet store(couldn't find advantage locally). I haven't seen a flea on her in 2 weeks. however she is still licking ALOT. I don't have a scale & could probably guess that she doesn't weigh more than 4-5 lbs.she has lost most of the hair around the tail and hind legs. I have noticed the occasional sore in that area also. Is there an ointment or cream that would not do any harm but bother her enough not to lick? Hubby suggested Vaseline but I said NO I'll write to you first.
thanks again, looking forward to your reply, Cheryl(frustrated Canadian)
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The text above is a follow-up to ...

-----Question-----
Dec.13,2006 we lost one of our 13 year old(indoor/spayed)sisters. Now we find the other sister was constantly scratching & licking, we noticed she had fleas.So we bought her a flea collar(Feb.4). Since then her licking & scratching has become worse, to the point where she has lost hair(on her back side area). We are unable to get her to a vet, because we cannot afford one. Any ideas on why she is doing this & is there anything we can do to remedy this. Today I've taken off the flea collar to see if this helps. We're hoping someone can help, we don't want to lose this one too!!!!Thanks Cheryl
-----Answer-----
Hi Cheryl,

I'm sorry about the loss of your cat. It was good that you took the collar off. Sometimes they cause more problems than they cure. You need to go online and get Advantage for cats. It is a once a month treatment for fleas. It works very well with very few side effects. You can also get this at a good pet store. She definitely sounds like she has an allergic reaction to the fleas. In the meantime you can give her Benadryl antihistamine. The dosage for cats is 4mg/2.2lbs. Give this 2 times a day. It should help her until you get the flea medicine and she has no more fleas. Good luck and let me know what happens.

Ciao, Karen

Answer
Hi Cheryl,

Sorry it has taken me so long to get back to you. I have researching a lot to try to help you. Zodiac is a good product for your cat. Since you have access to the Internet you can get a product called Tresaderm for her. This will help clear up any skin irritations or infections.
Her weight loss is another matter. This could be a sign of something going on internally. You should get her to a vet to have her checked out. To help her, feed her a stage 1 baby food like beechnut chicken or turkey. This is high quality food for her. Let me know what happens. Good luck.

Ciao, Karen