Thanks for using the forum on HCM.
From the description of the symptoms this could be an enlarged lymph node
in the inguinal region. This can be due to various reasons for which you require full assessment with your doctor. The other cause can be an inguinal hernia
which can also present with similar signs, the most important being a swelling in that region. The hernia can become sensitive once the sac enlarges containing contents such as loop of intestine within the sac. You should consult with your doctor for full clinical examination for proper diagnosis.
Feel free for further queries.