Hello ma'am and welcome.
The location you have provided is close to the region where your inguinal lymph nodes are present. These lymph nodes can at tines be palpated even during your period, but otherwise are related to infections. The only other possibility could be a swollen or infection hair follicle, I would advice you to visit your doctor for an accurate examination and diagnosis or write back to me using the premium service wherein you can attach photographs of the given presentation.
And no ma'am, there is no relation between masturbation
and swollen lymph nodes
Hope this helps.