Please try not to panic over Christmas; a lump which you describe could be due to more than one cause.  But you should go to see your doctor when things get back to normal after the next two days so that you can get some proper medical information as none of us here have medical training.  We are a bit thin on the ground at the moment so apologise for not replying yesterday.  I do hope you will enjoy your Christmas and while I can understand your worries try not to immediately think the worst.  Best wishes.  Annie