Hi K.! I bet you got plenty of responses, but, as a grandmother and wife of a retired doctor, I just have to put in my two cents. As for treatment of your baby, just keep him/her cool. Clothing may hurt his skin until he heals in a couple of days. A very light lotion that you normally use will help to sooth. Babies skin is so sensitive and new. It is recommended that you don't expose babies under 6 months to sun at all. After that keep them out of the sun still - using clothing, hats, canopies, play in the shade. When they start runninig around, if in the sun, apply sunscreen liberally and often and year 'round! Have your child get used to a brimmed hat at soon as you can and have putting on sunscreen a ritual. Stay out of the sun during midday as much as possible. Actually all this applies to you, too. Skin cancer is a very real danger, not a hyped up media fad.
As for your little one;s cold, use some lotion on the tissue and wipe softly. If they are too congested, consider a suction bulb to relieve his drips. Good luck!