I Have A Lump At The Back Of My Throat. Is It A Throat Cancer?

please help, for the last 3 days iv felt a lump at the back of my throat i cant shift, feels like rubbish but it wont go down or come up, i have just got over a cold and cough, but my nose is a little stuffy sometimes still, iv just had a lot of blood work done and nothing showed up, but im terrified its throat cancer! im 27 and do smoke! i dont have a sore throat when i swallow though and food goes down like normal! i tried to see my gp last week who listened to my chest and said all was clear and that i need not worry, but that wouldnt tell throat cancer woukld it? and she told me relax as my bloods were recent too, but again that wouldnt show up throat cancer would it? i do suffer from panick attacks and have trouble breathiing, so in november they gave me a chest x-ray and some nblood work done in hospital, so should i out this down to my cold?