I feel a jolt as I squeeze the tip of the penis glans. Every time I squeeze the tip of the glans I feel something hard like a bone - yes, I know there is no bone in the penis.
this mass is internal, only palpable but not visible in gland
What you are feeling inside the head of the penis is most likely naturally present - you may be feeling the jolt because there is an infection present, and this is most likely in the urethra or meatus. If you are sexually active or masturbate using some pressure it is possible an internal blood vessel has leaked and has caused irritation.
Depending upon when you first noticed this, or, certainly if it persists the only safe thing to do is to get it checked by a Doctor, or Urologist if you have access to one …