Lump Down The Throat, Difficulty In Swallowing, Diagnosed As Thrush, Taking Medicines, No Relief. Anything Serious?

Hi For 7 weeks I have felt a lump down my throat , one week ago I found the cause was a yellow, 1/2 inch long lump at the back right of my tongue , the lump is painless, It is only on one side and it looks dirty yellow and hard. I saw a doctor on Monday who said aargh don t know what it is she said she had to rule out thrush as my tongue was coated white until she could rule out something more serious, I paniced and saw a different doctor 2 days later who thought the lump could be a swollen tastebud but was unsure as it was painless, he told me to carry on with the thrush treatment and to go back if the lump was still there, I have finished the treatment and it s still there unchanged, I don t like to keep going back but it is hindering me swallowing etc, could this be caused by something serious?