Hi and welcome to HCM.
This can be STD
,but also it sounds to me like it could be clogged and inflammted gland which is common. If there is no vaginal discharge
then you shouldnt be worried. If symptoms persist you should also do vaginal swab to see the exact microbe which causes it and then it can be treated on right way.But if this heals spontaneously you dont need specific treatment. Just keep genital area clean and dry and dont wera clothes that provoke sweating. Wish you good health