Welcome Jenn
What a difficult time for you - you are so young, I certainly hope your tests are negative for cancer.
When I went to my gp with a lump on my neck I had an ultrasound that day, the radiologist did a needle biopsy on the lump there and then. It came back the next day positive for SCC. From there I had CT, PET etc to discover the extent of disease which turned out to be significant.
The pathology of the needle biopsy was able to direct the docs to the tonsil. Apparently cancer cells retain many characteristics of their origin (this is a non-professional interpretation).
The main site here is full of info regarding diagnosis etc. I found it very helpful on my journey.
Please let us know how you are progressing. Many survivors here have walked a similar path and will offer support.
I send best wishes and love from Helen