HELP!!! Seedlings have brown spots forming :,(

Hey guys this has never happened to me before but my 2 out of 5 of seedlings that are only a few weeks old have started to form brown spots on the leaves. The other 3 seedlings are in the exact same growing conditions so I don't think it could be a nutritional deficiency but I really need to get them healthy again because I think the brown spots are growing
Additional info: growing in foxfarm soil in solo cups with drain holes in the bottom, all seedlings grown from seed and all the same strain (satori), have been watering with nothing but distilled water, using 250 watt cfl light, please let me know if you need any more info

That's a pretty hot soil for starting seeds, so not unusual to have issues. Get a little cal/ mag in your water and they will likely grow through it.