The ongoing saga of Sasha's mysterious illness, or not

As I'd written before, Sasha has had a loose stool since the day I got her. After a few weeks, the vet diagnosed her with coccidia, we did two rounds of treatments, and she got a clean bill of health last week. But still, something wasn't quite right. She was taking frequent breaks when we would go on our walks (laying down on the sidewalk, mid walk, for a minute), something she did when I first got her, but something that stopped once I started treating her coccidia. It's back.

Then this week, her stool turned from soft to gloppy. Not a good sign, so I put her back on the ID dog good the vet prescribed (basically, a bland mix of rice and meat, I believe), and I started giving her pumpkin and non-fat plain yoghurt. At the same time, the day of the glop, she didn't want to eat any more of her kibble as a "treat" - she always would before. I called a family member/friend who is a vet on Monday, but never got a call back.

Today, her stool is still soft, though better than that first day, and this time there was a small bit of blood. I called my vet this time, and left a message. Still waiting for a call, and will call back again soon. Sasha, in the meantime, is acting remarkably normal. She's taking the kibble treats again (though I cut her off, just to be safe), and she doesn't lay down as often on our walks. Her appetite is great, she drinks, and is otherwise "normal."

I've done my own research, and there are simply too many possibilities, ranging from giardia, to more coccidia, to an irritated bowl from too much play, to "something surprised her," to all sorts of worse scenarios. The thing is, she doesn't have out and out diarrhea, and I've noticed that what she does have tends to come and go in phases. Her poop is never perfect, but it does get better and worse. All of which is making me highly suspicious that this might be giardia (but again, wouldn't she then have out and out diarrhea?).