Hi virgin-grower21,

pictures would help but if I understand your post correctly, you are feeding the 5 day old plants with nutes already? If so, this is a bad idea. You should not use nutes until the plants are around 2 or 3 weeks old. That would be the problem there, they're not ready for nutes. Flush them with ph balanced water (no nutes) and hopefully they'll be ok. (I'm not sure if you were referring to the seed leaves though).

However, if I've misunderstood your post and you are not using nutes yet, it could be heat stress caused by having your lamp too close to the plants. 5 day old plants aren't strong enough to be blasted by a 500 watt HPS light, make sure it's a good metre away from the top of you plants for a while and then move it down gradually over a week or so.

Another problem could be the heat. A HPS in a closet could cause it to be very hot in there, perhaps too hot. Either way man, I can only recommend that you read, read, read as this is pretty basic stuff and can be found all over the forums.

Good luck.