I hope I can help you here. Please understand that online no one can state with certainty what anything is, all I can offer is my best guess based on what you wrote. If it is a fungal infection you are treating, often they will take a long time to clear up...sometimes it requires a few weeks. Having said that though, I do not know that yours is fungal; you may have a bacterial infection you are confusing for the fungal jock itch.
It may be though that the fungus might be resistant to the lotrimin; there are other antifungals available over the counter. The active ingredient in Lotrimin is clotrimazole. Look for creams that do NOT have this ingredient; a good antifungal ingredient is Terbinafine, found in Lamisil cream, and ketocanozole, found in many preparations.
Please avoid steroid ointments, all this does is make fungus grow more.
If the fungus is not healing even with a switch in OTC creams, it may need prescription medication (or be bacterial; meaning you would need antibiotics)...in that case, you would need to see your health care provider for proper diagnosis and treatment.
List of antifungals here: http://dermnetnz.org/treatments/topical-antifungal.html
More information on jock itch here: http://goaskalice.columbia.edu/jock-itch-treatments
I hope I was able to help, and that you feel better soon,