Squamous cell carcinoma unknownboard

I am a 55 y.o. woman (never smoker, non-drinker) recently diagnosed with metastatic poorly differentiated squamous cell carcinoma of unknown primary. I live in the US.  I am still hoping that a primary will be eventually be found be as of now (2 months into my diagnosis saga), it is still not clear what it is. I have three involved lymph nodes — 1 right supraclavicular node and 2 nodes in the right side of the upper-most part of my thorax (at the 2nd and 3rd thoracic vertebrae level). I am in the US and am being worked up at Moffitt, a major cancer center I’m FL. 

Last week, I met with two head&neck oncologists at Moffitt who told me that they are really pretty sure I don’t have a head and neck cancer. A recent CT scan of the chest showed three small irregular nodules in the upper part of my right lung (close to my involved lymph nodes) which are pretty clearly metastases or primary tumors. The problem is that this area of the lung is very difficult to biopsy. So they proposed doing a biopsy of another lymph node and comparing the results to the first. Somehow this might give them a sense of where the tumors are or might have been.

i will also be having an endoscopy to check for esophageal cancer, but I somehow doubt they are going to find anything (I had not one, but two endoscopes done about 18 months ago and in each my esophagus (and everything else were completely normal.) Also, I have no symptoms. 

So, I am wondering how can they tell if a lung nodule is a primary or a metastatic without biopsying the nodule. How likely is it that they can get an answer by comparing biopsies of different lymph nodes, or is this just a shot in the dark?

I am still feeling confident that they will eventually find the primary. However, when I expressed this confidence to the oncologists at Moffitt last week, their response was more hesitant and pitying than I would have liked (it was definitely not — don’t worry, we are on this!)

what happens if they truly cannot tell me where the primary is? Do oncologists just make their best guess as to the treatment plan? And do patients accept this kind of guesswork?

Should I be doing anything else to move my case along? The oncologists already told me they would bring my case to the Moffitt tumor board meeting and get extra input (I think this will actually be the second time before the tumor board for me). I suppose there is not much else I can do (going to Moffitt was already a second opinion. I also have local oncologists who are equally perplexed.)