I know this must be so overwhelming, especially considering the battle your mother has just had with cancer. I hope I can give some insight. I would like to ask a couple questions regarding your mother's experience in effort to give better advice:
(1) How large is the lump? Is it the size of a quarter, golf ball size, smaller, larger? Try to give me a general idea of the size. Has the lump gotton smaller or larger, harder or softer since removal of the tube?
(2) How long was her feeding tube in place? It is not uncommon for scar tissue to form around a feeding tube depending on how long it has been in place. Scar tissue is hard and doesn't have the elasticity of healthy skin. That could be a reason why the tube was leaking in the first place.
(3) What kind of feedings was she receiving through the tube? Usually tube feedings are in the form of liquid or thickened liquids. She may not be used to handling solid food after receiving only liquid feedings for quite some time.
(4) Before removing the feeding tube, did the medical staff slowly start giving her soft foods BY MOUTH to get her used to having semi-solid foods in her stomach?
(5) When you say she is experiencing discomfort, does it also occur after eating? How does she tolerate fluids?
(6) Does the operative site still have any leaking of blood or other kind of drainage? Is there any sign of infection at the site (redness, leaking of pus, foul odor?)
My main concern is that she is that lying down causes discomfort. Please answer my questions as best as you can. Especially my 1st question and my 6th question. I will be looking for your reply. I hope your mother feels better soon. Best Wishes