Enlarged tonsil with white lump

Hello. Four days ago I discovered a white lump at the bottom of one of my tonsils. I can feel it when I swallow and it feels like there is something stuck in my throat. The tonsil is also bigger than the other one and looks a bit misshapened. I went to see an out of hours gp yesterday (Saturday) who described it as a 'pustule'. He said we should treat it as an infection to start with and prescribed me antibiotics. He told me to see my normal gp should the lump not go. I have a lump on my thyroid on the same side which was diagnosed as a benign nodule in the summer. I am getting occasional throbbing and light aching around the whole of the same side, on my neck and up to my ear. I suffer with tonsil stones but this lump is definitely not one. I am worried and thinking the worse. I would appreciate any advice and to hear if anyone has has similar symptoms. Thank you.