My son has a sunburn after camping with his friend. His sunburn didn't look bad. Treated with aloe Vera, solar Caine and Motrin. Now he has a bump on his shoulder where sunburn is but feels like a bone. It is like a hard blister. Another one is forming on his other shoulder. My son never really looks badly sunburned but it is like he burns from the inside out because his skin never gets bright red but painful to touch or wear clothing so it is hard to tell how severe. His friends parents said they used the sunblock I provided. I concerned about these hard cysts that have formed.