Where did you get the straw? The bedding may be the culprit. Straw or hay can be dusty and moldy, or it can grow mold quickly if it gets damp. Plus, it is hard for chicks that young to walk on. I would get a large clean rubbermaid or similar plastic bin, lay several layers of papers towels down on the bottom and transfer the chicks over to it. Clean and disinfect your drinker and feeder. Put about 3 tablespoons of sugar per quart of water in the drinker and give them nothing to eat but a good brand of starter crumbles. I like Purina Start n Grow, but there are others. Put the lamp on them and make sure at least half the brooder is holding a steady 90 degrees. Use a thermometer. I know a lot of people say just watch them, but it doesn't sound like you have enough experience. Just get a thermometer and put it under the light. Make sure they can travel easily in and out of the range of the lamp. In other words, arrange their drinker and feeder so they don't prevent the chicks from moving freely around the brooder.
Basically....start over from scratch as if they arrived today. I think you've either got something going in the brooder where they are now (I suspect the straw) or they have been chilled too long.
Only use the sugar water for a day or two. Change the paper towels several times per day. After three or four days, you can remove the paper towels put them on clean pine shavings. Reduce the temperature by 5 degrees per week until they are about 6 weeks old. Keep them out of a draft. If they are in the house, make sure they are not in the path of an air conditioner vent or fan.
Good luck and let us know what happens.
UGCM