Maybe a swollen lymph node?
Have you been sick recently or started any new medication?
Could be what is called "Calcified Nodule" I had one like you described on my knee, the doctor removed it, took a few minutes and it never came back, these kinds of lumps are normally benign and nothing to worry about. If it gets bigger or hurts, then I would see the physician however.
Thanks for the input. It only worries me because just before the lump appeared I had been extremely fatigued/weak; which still continues. I guess it could be an infection-but, other than the fatigue and weakness, nothing else out of the ordinary. I will probably go see someone about it.