Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it seems that itching at the brief line that is worst in the evening seems to be due to a condition known as Jock Itch.. It is an infection of the groin region and occurs commonly due to fungal infection while can also be due to bacterial infection.. As the area of the crease in the groin region is more prone to accumulation of moisture and sweat it leads to maintaining a favourable environment for bacterial and fungal overgrowth.. Other cause can be obesity, poor immunity,excessive workout leading to sweating and friction.. I would suggest you to wash the area with warm water and mild soap and pat dry.. Apply a combination of antifungal and steroid ointment.. Avoid using any harsh chemical containing detergents and also avoid using any bleaches and fabric softeners.. You should wear loose fitting and cotton undergarments.. You can apply a coat of zinc oxide ointment over the area as it will have a soothing and sedative effect.. Make a solution of one part of vinegar and three parts of water and soak a wash cloth in it and place over the infected area.. In case if it still does not resolve consult an Infectious Medicine Specialist and get evaluated. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.