Hi. I'm Dr. Lee and will do my best to help.
Is the hair loss only on the tail?
And the hair loss is on both the end of the tail and near the rear end?
Any other area with hair loss?
So are there any hair loss aside from the tail?
Thanks for the info.
What you are seeing is likely from flea dermatitis or contact allergy or behavioral issues such as anxiety. It is best to have her go see your vet for exam and get steroid and control the problem. If that is not possible, then you can try giving her some human Benadryl at 1 mg per pound of body weight every 8 hours. Also, I would suggest to discontinue all topical products you are using currently. If there is no improvement after 2 to 3 days, then you really should take her to your vet for a checkup.
Please let me know if you have any questions or concerns. Thanks.