Hi Chloe.  Welcome to the forum.

Sorry to hear you're in this situation, but most mouth lumps turn out to be harmless. I discovered a lump on my lower jaw inside my mouth last Xmas.  The dentist checked it out and said was something called a Torus  - which is Latin for Bony Lump.  It's completely harmless.  I also have another harmless lump inside my cheek, caused by friction against the teeth.  Again it's harmless.

I haven't had a referral for a mouth problem but a couple of years ago I had a referral for a persistent sore throat.  At the first meeting with the specialist, he took a medical history, looked inside my mouth, and then put a small endoscope up my nose and had a look around.  At one point he looked down at my vocal cords and watched them working while I spoke.  It wasn't painful or uncomfortable. He then referred me for an MRI, which found nothing wrong.  Then I was referred for a Panendoscopy under general anaesthetic.  That also found nothing wrong.  As you can imagine, I did get pretty scared at times by all this, but in the end no cancer was found.  Of all these tests, the MRI was the worst! 

Incidentally, if anyone finds an unexplained mouth lesion then you might find it better (and possibly quicker) to see your dentist rather than your doctor.  Dentists are far more familiar with the mouth than doctors, and if necessary they can refer you to a specialist for rapid evaluation and any treatment. 

I agree with seeing the dentist, I went for a routine check up and the dentist spotted a white mark on the side of my tongue, he referred me and within a month or so I was seen by someone who took a biopsy and cut the white mark out there and then. Luckily the biopsy was nothing to worry about. My dentist always has a good look around my tongue etc for any abnormalities.

I agree with seeing the dentist, I went for a routine check up and the dentist spotted a white mark on the side of my tongue, he referred me and within a month or so I was seen by someone who took a biopsy and cut the white mark out there and then. Luckily the biopsy was nothing to worry about. My dentist always has a good look around my tongue etc for any abnormalities.