tail rubbing

[DAldr94141@seahorse.fsr.com]

Hi. I have an appy who never rubbed her tail till recently. She was wormed in 
Sept. and I neglected to worm her in 2 months so it was 3. She rubbed it a 
week after being wormed so I checked between her udders. Sure enough, there 
was a LOT of gunky crap I peeled out of there. I thought that would take care 
of it but once again, she rubbed. Maybe I didn't get it all out but I only 
feel a small tiny tidbit compared to what was there. Is there something I'm 
missing? Has this turned into a bad habit? I'll go and clean her with warm 
water and see what happens but is there something else? I wormed her with 
Strongid. Thank you in advance. Deb
P.S. It's not the top of her tail, it's more like down the middle of it and 
it gets to be a tangled mess.