Hi, I Had A Remedial Massage A Few Days Ago

Hi, I had a remedial massage a few days ago and the physio found a hard lump on my left hand side. It is on my waist under the back of my ribcage so to speak. It is only mildly sore when I touch it but it is the size of a golf ball if not slightly larger. When I stand up straight you cannot feel it or see it (purely under the skin)... but when I slightly tilt to the right you can feel it easily. I am concerned and have booked a GP appointment tomorrow. The physio was also slightly concerned. I had my gall bladder out 12months ago and during the surgery the surgeon found I had a very large lymph node so he sent it away for testing and it came back fine... I am a 6ft female, 80kgs generally well... although have chronic atrial fibrillation at age of 37years which I am having treatment for with cardioversions. Other than that...that is my history.