Just wanted to add that I read your original post wrong (oops). I was thinking with was at the tip of the tail. But, what you describe is a 'bump' at the base of the tail. How big is the bump?
I think it sounds more like an abcess (or something similar) than a tail break. For your cat to break their tail at the base, I think in most cases you would KNOW it happened immediately. They would be in pain.
Btw, I had a cat that had an abcess in the same area (I think it is common for some reason), but don't beat yourself up because they can come on gradually...so it would take a while to notice.
I definitely think your cat needs to be seen by the vet.
Please keep us updated.
I think it sounds more like an abcess (or something similar) than a tail break. For your cat to break their tail at the base, I think in most cases you would KNOW it happened immediately. They would be in pain.
Btw, I had a cat that had an abcess in the same area (I think it is common for some reason), but don't beat yourself up because they can come on gradually...so it would take a while to notice.
I definitely think your cat needs to be seen by the vet.
Please keep us updated.