Trained Dog Peeing Randomly in House

[alward]

So, I have this 7-8 year old beagle, that I got from a rescue about 3 or so years ago. She's been having some strange peeing habit in the house lately.

Most of the time, she is fine. She's on a regular- go outside 3-4 times a day schedule and normally goes to the door if she has to go other times. I know she can make it a long period of time, because she goes 8 hours a day without ever going in the house while I'm at work.

But lately, she's been peeing on my carpet, when I'm home, right in front of me, with no warning. Not in the same place, random places, random times. She's also got into the habit of getting up in the middle of the night and peeing. This is not a daily thing, but up to 3x a week.

I've been monitoring her water, I've been crating her at night and when I'm gone for long periods of time otehr than work... but it doesn't seem right to crate her when I'm home with her, and I've had her to the vet and she doesn't seem to think it's a UTI.

How can I get her back on track??? She's got lots of doggy issues and I put up with a lot, but peeing on the carpet is not something I can deal with very well.