I recall going through a similar train of thought. I had a swollen gland. I felt fine otherwise. How can this be cancer? However, I had a gut feeling something was amiss prior to my diagnosis.
I really didn't feel anything until just before my neck dissection and even then it was just some pressure from the tumor pressing on structures and nerves. No pain at all.
I know... "we" know what you're going through. It's going to be Ok. You're going to be Ok. Take a deep breath, read up here and learn as much as you can during the following weeks and seek a second opinion regardless of how things go next week.
Positive thoughts and prayers
"T"