What Does A Lump On The Shin Indicate?

This morning after doing some therapy for my injured knee (my trainer said i had tendonitis and my doctor said i have tissue damage so im not sure what is exactly wrong with my knee) i realized that i had a large bump on my upper shin or right under my knee. there was no bruising, redness, or sensitivity to touch but hurt pretty badly and the pain got worse throughout the day. The lump is over an inch long, is circular, and stiff/hard. as i lay in my bed right now, it hurts a significant amount more than this morning. there is also a tingling feeling or the area feels like it “fell asleep”. The swelling has gone down but the pain keeps increasing. what might this mystery lump be?