What to do about possible mold in client's home?

Strange question, I know, but I believe that the house I'm sitting in has a mold problem, and I am quite certain that the owners have absolutely no clue about it. They are very nice folks, take wonderful care of their well mannered dogs, and they have a clean and well kept home. However, I noticed some water damage on their ceiling my first (of 4 days/nights), but it looked old and dry like it had been there for awhile. I thought nothing of it because I did not want to assume that it was recent due to the immaculate state of the rest of their home. Though now that it has been raining all day (day 3), I have confirmed that they have a leak in their roof, and upon further inspection around the area of the leak, and I found plenty of evidence of water damage in several areas (walls and ceiling) in a different room off the living room where I first noticed the old but dried water damage. The corner of the carpet behind the door where I found water dripping was very wet, musty smelling, and appears to have black mold growing on it, which is not that uncommon where I live. I don't know if I'm being overly paranoid, but I woke up the first morning of my stay with an unusually scratchy throat. I thought I was getting sick, but after I went home for a couple hours to take care of my dogs, shower, eat and head back, I felt much better. A couple hours after returning to the home, so did my dry and scratchy throat. Same thing happened on day 2, and now again on day 3... I still have one more day to go, and I have alerted the owners of the water leak I found, but I have not received a response yet. Not surprising as they are on vacation and have been slow to respond to my other messages (of less importance). I REALLY don't want to stay anymore, but there's no way I'm going to abandon the dogs, nor do I want to abandon my commitment... what do I do?! :(