It's almost guaranteed that a dog will have congested anal glands if their bowel movements are chronically too-soft. The pressure of a regular firm stool usually keeps the anal glands emptied nicely.
Her bottom must feel a bit sore right now. If you have aloe vera lotion, you could try some on her poor little butt. Just put some on a cotton wool pad and wipe for a moment or two. I'd do that regularly and I'm sure the irritation should die down. Anything worse like inflammation or pus etc -take her back to the vet asap.
About her loose stool....I imagine that over this time she's had that, she has had stool analysis? In case of parasites, or any inflammation etc
Has IBD (inflammatory bowel disease) been ruled out? Or other possible causes?
Or is it "idiopathic"....which is vet-speak for "we don't have a clue what causes it" !
I would definitely have those tests run ...but I can imagine you have already.
Have you tried white rice and boiled chicken breast or chopped hard boiled egg for a couple of days? I know everyone says fiber is the answer for loose stools and diarrhea, but in my humble experience I have NEVER found that to help! It may even be she is a bit sensitive to high amounts of dietary fiber (as I am myself increasingly with age!)
Sometimes a bit of easy to digest, rather "binding" food for a couple of days can re-set the balance. Whether it will change anything long term is doubtful, but it might relieve symptoms for a few days at least. Or in case fiber has been causing mild irritation, might give a day or two for some healing to take place?
Don't keep her on those foods for more than a couple or three days at a time, because those foods don't contain enough nutrition for a dog generally though.
Maybe your vet can help? Or maybe a diet like Royal Canin or similar for sensitive gut and digestive issues might be helpful? Ask if they may be able to provide samples first to see if it helps before buying a bigger bag, as it isn't cheap food?