Also if you need to use the cream again in future, it may help just to use it on the spots themselves, rather then all over the affected area.
If you used an anti-acne cream regularly for some period of time and if this is occurring soon after you stopped using the cream, then it may be that the cream has made your skin very very dry, probably made worse by the cold climate. I was prescribed acne cream (can't remember what it was exactly) from my doctor and I found that if I used it every day, after a week my skin would be extremely dry and sore. This may be the same for you and since the groin area can be more sensitive, this may be why it is painful. Using a very good moisturiser should help. Also, you could try to eliminate other factors that can make dry skin worse, such as central heating or lack of mosture in the surrounding air (humidifiers can be helpful). If you use a moisturiser, try to use one that doesn't contain a lot of harsh chemicals. Hope this helps.
Yes, it would be perfectly safe, and a good idea. You can't damage skin for good with Lamisil spray, by the way. If the moisture application doesn't help, you should ask a doctor. A medicated anti-inflammation cream, possibly containing hydrocortisone, may help. Minimizing friction is also a good idea.
Take care.
Dr. Rockoff