Do the spots look like grains of salt? If so it's probably
ICH which can be fixed by increasing the temp slowly to 83-84F. Leave it there for at least 2 weeks. Increase aeration to make up for the lack of oxygen in warm water and vacuum the gravel really well to get rid of the spores.
I don't have experience with fry, so you might want to wait for other members who do to make sure they can with stand the increased temps.
Do you know the readings for the
ammonia nitrites and nitrates?
Often times stress from an uncycled tank can bring on illness.
I notice you don't know about the
nitrogen cycle here's an explanation of it:
http://www.fishlore.com/NitrogenCycle.htm
I hope your babies feel better soon.