It does sound like the brooder is too hot. Do you see them panting as well? (beaks open) If you are brooding indoors, a 250 heat lamp unless placed far enough away from the brooder is going to be too hot. I use a 250 watt for brooding outside, then I switch them within 2 weeks to a 150 watt bulb.
The blanket is over the other half of the container not near the heat lamp-I did it this way because I'm in Southern California and the heat last week was 90 degrees, which was pretty warm, and when I put in the hotter bulb the temp shot up too high-so I have a 60 watt bulb over half of the bin and a blanket over half of it at night (not near the lamp) and the temp has been consistent at 90. But its week 2 now for me so I'm not going to need the blanket anymore. I agree, even being new to this, it seems like its a temperature thing from the sound of it...beaks open and panting. My chicks have been spread out in the container-which I'm about to build a bigger one too-7 peeps are definitely getting crowded in there. My chicks are happy and healthy so far-except one that keeps pasting up...I'm fine for cleaning her, but I can't figure out how to get her from pasting up...I posted in the injuring/sick forum for this.