Thanks for the query.
Your condition could be eczema
or any inflammation. As you said, the pink discolouration may be due to scratching. With the description you gave, it doesn't look like a sexually transmitted disease
Commonly it is caused by fungal infection
, but can be bacterial or viral too. Symptoms are aggravated by heat, moisture and friction.
Loose clothings and keeping the area dry will bring the symptoms down. If it persists, you will need to visit a dermatologist
. They will be able to rule out many other simple causes for the itching and provide you with ointments
which will reduce the itching and heal the sore area.
Hope I have answered your query. Please let me know if I can assist you further.