Oblivion Feather Glitch?

I have been playing Oblivion for sometime now completing quest lines and catching various side missions here and there, but as I progress further to fulfill my own personal quest to complete every quest in Cyrodill I find that my feather has decided to decrease all on its own. I did have a feather of 510 and now it has decrease to 495.....this of course didn't decrease because I had something enchanted equipped . Please help!