Hi I'm Really Worried As Have Been To My Gp

Hi
I'm really worried as have been to my gp a few weeks ago with lumps at the back of my tongue + also a blackish lining on my tongue. This went away but now is back, it is making me need to swallow really frequently + feels as though something's stuck in my throat. I felt down with my fingers + right at the back of my tongue there is a gaping flap which I have never noticed before. I gave up smoking at Christmas but am panicking these may be signs of throat/ mouth cancer?
Thank you