Wise MNers, my 8 month female fur-brain has a lump at the base of her tail. It's to the side of and under the tail. I can see the fur not sitting right and can feel the lump. If I squeeze it gently she squeaks 
My hunch is blocked anal gland or possibly an abcess.
It's Sunday and I can't get to the vet until tomorrow night. She's ok in herself, eating, playing etc as normal.
Do you think my diagnosis is correct and i don't need to rush her to the vet.