Is it safe to use lamisil cream for 2 weeks for jock itch even if not directed by a doctor or is it only to be used for 1 full week and then stop? and is it true the lamisil cream continues to work on the fungus after treatment for 3 weeks?

If you're using the nonprescription product you should use strictly according to the directions. Fungal infections are slow to eradicate and if you don't treat them long enough the infection will return. If it's prescribed by your physician or dermatologist, follow their directions as they have examined you closely before prescribing. Treatment for jock itch is usually one week but may take longer