What Causes Sudden Blockage In Food Pipe While Having Food?

HI my mom is suffering from food pipe blockage. She feels that when she use to have food and not all the times(say drinking water). We consulted a doctor and he said that it is due to less blood in body and advised to do endoscopy. Will less blood in body cause the food pipe to shrink. Please advice me. I am scaring it could be throat cancer. She do no have any other symptoms like cough fever. She feels the pain only when having food