I Have Been Feeling A Lump In My Throat For

I have been feeling a lump in my throat for 1 1/2 years now--my throat doctor checked and said see my thyroid Dr.- whic I did--she ordered an ultra sound of my throat(which was difficult for me swallowing)-nothing! then she said see my lap-band Dr.-he did an endoscope -nothing- loosened my lap-band slightly, which helped for a short time- but the problem is back! I seem to have no difficulty swallowing normally- but in the later afternoon and evening, or when I lay down this lump puts pressure on my throat and it concerns me---