rabbits are herbivores, but truth be told rabbits in the wild don't eat all that stuff we seem to feed our pet rabbits. while they might indulge in some radish leaves or other vegetable leafs from someone's garden they stick to the meadow grasses which are healthier for them, too many vegetables especially anything with a higher sugar count can and will make your rabbit sick, or obese, it also shortens their life span.
What ever the rabbit has it is definitely not Cocci, it is not his or her urine either, chances are the rabbit chocked on something he or she ate and brought it back, at which point what comes up will be a yellowy foam with what ever what causing the problem in the first place. This is the reason I asked you what you were feeding your rabbit in the first place.
Do yourself and the rabbit a huge favour, take him or her off all those extra vegies, the more vegie greens he or she eats the less they eat their actual pellet and hay and this can cause massive deficiencies that of course you cannot see form the outside by looking at your rabbit. stick to a couple things like romaine lettuce and another favorite like Basil or curley parsley or even spinach. as I mentioned, I only give mine romaine, and an apple slice here and there and maybe a slice of carrot once in a while. I do give them spinach when I buy it fresh and basil, but that is only during summer months and maybe like once or 2x during the summer.
Mind you in the summer I let nature take its course while I provide the pellet and fresh meadow hay, I allow my rabbits to be outdoors all summer long, they have a completely fenced in run, including the bottom with thick wire so the grass etc will still grow through it, there is a rabbit hutch out there that I never lock. If its warm enough outside, that is where they are at. they get to forage through the grass and eat dandelions, and clover, and I give them logs, they like to scratch at the logs I think they wear down their nails this way.
Anyhow I do just think that she hacked up what ever was stuck in her throat.
Ema