identifying a lump

hi all,

a couple weeks ago i noticed a lump ~1.5" wide x ~2" long x
~0.3" high on the back of my right leg oriented lengthwise
up and down my leg. it is located just below my buttock and
close to my groin. if i had to guess i'd say it's centered
axially along the top of my semitendinosus muscle. when i
palpate it it feels like muscle (fyi, i'm not an expert
palpater but it doesn't feel like a fluid filled cyst).
when i apply more pressure i can reduce the height
significantly (as though it's deflating) so that it becomes
more difficult to notice visually. after a few minutes it
returns to it's previous height.

can someone direct me to some resources for palpating lumps?

my gp (a naturopath with 20+ years clinical experience with
MDs) said she thought it was just muscular tissue and didn't
think it was anything to worry about.

if i wanted to get it definitively identified what type of
health professional would most likely be able to do so?


thanks,
david
.