How old are they? Are they on medicated feed or non-medicated? Chick starter could be medicated to reduce the likelihood of coccidiosis, but older birds shouldn't consume the medicated feed as it works by blocking a specific vitamin to starve the parasite. Some runny poop is considered normal, following link is to a site that has images of several varieties of chicken poop...
https://www.fresheggsdaily.com/2016/03/all-about-chicken-poop-brown-black-and.html The vinegar will help keep the water cleaner longer as it inhibits fungal growth.
How old are they? Certain herbs could certainly cause diarrhea but I don't know if dill or oregano would...best to just feed their main feed, no treats, and plain water to see if it clears up. ACV isn't all that it's hyped up to be...a good treat would be mashed up boiled eggs, if you feel that you have to give them a treat.
I second the opinion to treat with boiled eggs if you must give treats, as it won't cause them digestive problems. Mashed up boiled eggs are excellent camouflage for medicines as well. Chickens lack the enzymes necessary to digest dairy, so until you have their poop issues resolved, I'd not add yogurt. That said, I do use yogurt after any illnesses that required the use of antibiotics (after the treatment is complete) to help restore their gut bacteria. Do not feed scratch, it dramatically reduces the overall protein in their diet and offers next to nothing nutritionally, it's kind of like humans eating potato chips... sure, they're made with veggies, but they're not nutritious.
If these are chicks, and if they're not on medicated feed, then I'd consider medicating their water with
Corid (to treat coccidiosis) as soon as possible. The coccidiosis is very easy to catch, and chicks (those recently exposed to grass and soil) suffering from it typically die before you get to the 'bloody poop' stage of the disease. The medicine to cure coccidiosis won't hurt them if they don't have the disease, and the medicine available in chick starter will
NOT cure the disease, it only acts as a preventative measure. They can still get coccidiosis if they are ingesting medicated feed, it's just less likely. Sorry for writing a book on the subject, but didn't want to risk this being a symptom of something important to your flock and not saying it.