They will recover eventually, but for future reference do NOT use Deep Heat, Dencorub, Finalgon, Voltaren cream or any related creams in that area. Also avoid things like Isocol rubbing alcohol (unless you are some sort of twisted masochist )

If you need to apply heat to the groin area, use a WARM (not hot) heat source - a hot water bottle wrapped in several layers of towel is one way to go.

I shall restrain myself from enquiring too deeply into the nature of the activity responsible for the original injury.