@le_bwah @Nabiki @007Sean
Hi, an update.
I had check the temperature from the beginning, but at the hottest spot is 37ºC. So it should be ok. Also, I've been observing the chicks so I know temperature is right for them. They have a range of temperatures from there.
I've figured out one of the chicks who has diarrhea. It's not all of them. Today most have normal droppings.
It's one of the ones I left alone during the hatching because it had one of the biggest air cells. Didn't give it any security holes or anything. But it only made it to external pipping and it got exhausted. At the end I had to peel it like a boiled egg. It was ready and it came out fine but very tired.
It's a lot more tired than the rest, and I see it's also kinda isolating sometimes. It drinks and eats, but gets tired so much easier than the rest and starts laying down wherever (which is normal for quail anyway but it's doing it a lot more), like I'm drinking and suddenly I'm taking a nap over the waterer.
I'm worried about she/he. I've been asking for something similar to nutri drench but no one seems to know it or have any equivalent here. I'm looking online but I'd be helpful if someone knew how to make a homemade version. I'm giving them some raw yolk for now.
I know there are other birds with diarrhea. I think they're maybe 3 or so from the droppings.
And about Propylene Glycol, I'm not a chemist. I'm a physicist. And in fact I hate chemistry but they forced me to learn a little chemistry in my degree and I'd say it's there in the formulation to act as a solvent. There are certain substances which don't disolve well in water or other more commont safe solvents. I know propylene glycol it's used sometimes to disolve medicines and I guess some of the components of Nutri drench need it, or for whatever the reason they've used it (maybe it worked well and was cheaper). In any case, the dosage of any substance it's what makes it dangerous or not. Like for example bananas are radioactive in fact because of the potassium isotope, but you can eat them safely. I don't know about the safe consumtion of PG but if you find some well done research about it you can make a better judgement. But I totally agree that very often you find recommended doses of things by WHO or FDA or whatever which end up being totally wrong and they change them, or some parties fund research so it comes out favorable for them. You really need to end up reading all the papers they publish and make your own judgement to get some sort of insight. Also, it's always better to avoid anything potentially toxic if possible, I totally agree with that. Nutri drench, even if it weren't so good, I guess it's a matter of benefits vs risks. I guess a chick needing nutrients so badly maybe it's more benefited from taking ND than not even if PG it's not so good for it. Also the fact that something is used as antifreeze or whatever other use doesn't necesarily make it toxic or dangerous. Substances can have different properties and uses. Water is safe to drink and it's also a great cooler agent due to its high specific heat capacity.
Anyway, those are my unasked thoughts about the topic.
And as a side note, always beware of the titles of articles and whatever facts you read around. A lot of them are just there to induce some sort of emotion in you. Like for example you can read "this disease it's twice as deadly as this other one" and it sounds bad, but if the mortality rate of the first one is 0,1%, then the other one has a 0,2%, which it's still, pretty low. Even if it's twice the first.
But, our FDA classifies it as “generally recognized as safe” for use in food). 
