Hi Ilex, you might want to discuss this with someone else too - someone that's close to you - whether you should go for another consultation. Btw, you haven't mention if you had the Xray. Get one if you haven't.
The lump hurt after you left the office could be due to the doctor pressing on it. If the lump is getting very obvious and you can see that there's a lump there even without touching it, then maybe u want to check it out again. I'm sure the doctors that you have seen before were orthopedics?
If the lump have started to hurt badly, it's another sign to make you go back to the doctor. However, if you are generally in good health, eat well, exercise well, no significant weight lost, no pain... perhaps you can just watch that lump and see if any new symptoms develop. However, it's really up to you to decide how determine you want to get to the bottom of this. Look for doctors that have more experience in lumps/tumors and maybe they can help you more? Good luck and let me know how things go.