Unfortunately, that's what I can't know. I'm more concerned about the loose droppings which can often arise from bacterial infection in parakeets. If possible, I would separate your birds into different cages so you could tell which needed treatment.
Until they can be attended to by an avian vet, please heat up their environment to 85F by means of a 100W bulb shined into their partially covered cages (not at night when they needs to rest) or by taping a heating pad set on its lowest setting to the sides of their cages. If they appears weakened remove their perches and put their food and water on the bottom of the cage along with them. Add a water soluble avian vitamin such as Oasis brand to their water at half of the recommended dose so as not to make their water distasteful. Add a calcium supplement such as Calcivet or Calciboost to their water. These supplements are available in pet/feed stores. Avoid over the counter antibiotics designed to be placed in their water. They won't be effective if only because an ill bird won't drink enough to medicate itself properly.
Nutritional imbalances are a common cause of illness in our pet birds. What has their diet consisted of, please? Seeds should compose less than 20% of their diet. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat.
Please respond with further questions or concerns if you wish.