I have a 4 year old spayed Pug girl.  She wasn't particularly difficult to house train but every now and then she was weeing in the house, sometimes right in front of me and sometimes on my Chows bed which absolutely disgusted him.

I went back to basics, taking her out, telling her to go and then lots of praise.

I am now in the position that I can't trust her to go by herself, if I just let her out with the others she waits on the back door step until I appear, then she won't go onto the grass unless I go.  When we get to the grass she just stands there looking at me, I have to tell her to go several times before finally she goes.  She's like this with my husband too and even first thing in the morning when she must be busting.  If we spend the day out in the garden she will just go as and when she needs.

She did have cystitus at about 1 year old and had juvenile vaginitus on and off until she was 2 which cleared up when she was spayed, all this however was before going back to basics with her.

This can't all be down to being a Mummy's girl can it?

I would have her checked again ..take a smple to the vet ,there are so many things it could be ..eg: she may have crystals in the bladder. Some bitches who ar spayed can have problems.
If results come back  normal then I would do as you are doing back to basics at any age sometimes is required.

I also give my girls garlic from dorwest and cramberry complex  supplement from the vet.