I have a lump on my sternum, anybody with the same?

I have a lump just in between my bones. Ive had the lump for approx7 yrs and every now and again causes me great pain. It hurts when knocked or touched. I have been to the doctor countless times always to be told its nothing to worry about. I have finally got the dr to agree to giving me an xray, my appt is next monday but was wondering if anybody else has the same condition and if they know what it is. Im female and 36 yrs old. Type 1 diabetic with 2 children. I had my gall bladder removed approx 10yrs ago as they thought that was the cause of the pain, obviously not though as I still have the severe pain, plus a lump. Thanks in advance ♥