Seeking Counsel! (4 babies died last night)

Hey Everyone, 
 
To get you up to speed, our lil fry came out of dads mouth this past Tuesday. Since then I've had them in 5 gallon tank with live sand, several rocks from my main aquarium, a heater and a bubler - no filter because it produced too strong a flow and have been doing frequent water changes (2.5 gallons every other day). As for diet, they've been snacking on a healthy portion of live baby brine shrimp. So now here's what happened:
 
Last night, everyone seemed fine. We ran tests on the water and noticed the Ammonia levels were slightly elevated so I decided to go ahead with another water change (probably 3 gallons). Well I feel I probably should have pre-heated the water because the tank temp dropped probably 8 degrees. After the fish seemed stressed and most clung to or near the bottom of the tank. After several hours, and some new baby brine shrimp, the majority seemed to perk up. Well this morning I woke up and 4 of them died, several don't seem to be doing good and the rest seem normal. 
 
Do you think it was the sudden drop in temp? Am I over feeding because they never seem to eat all the baby brine shrimp in the tank? I'm filtering out the baby brine from the breeding water and eggs, but could it maybe a bacteria problem?
 
Any insight or opinions appreciated.
 
 

What is the actual ammonia reading?  I use a SeaChem Ammonia Alert badge and dose ClorAm-X as needed to keep ammonia at "zero".
 
8 degrees is an awfully large drop though...

Don't let fear and common sense stop you! =]

Ya the temp drop has me worried the most, but since some of them still seem to be struggling I dont know. The ammonia was right near .25 ppm. 
 
My gf did some research and think it's because we're not feeding them enriched brine shrimp. She says without enrichment they're more susceptible to shock. Does that sound legit? 

Things are going from bad to worse, they're dropping like flies. 3 more died since waking up and things are deteriorating. I have no idea what happened