Thanks for writing to us with your health concern.
You actually need not worry about the node in your underarm.
It is very common for lean people to have palpable nodes.
The area you describe by the side of your crotch is also a common area.
In my opinion, there is no need to get a third opinion on the node in the axilla, but yes, you could see a gynecologist to confirm that the genital lump is indeed a lymph node.
All the best
Please feel free to discuss further.