Hi I Have Recently Found A Skin Coloured Lump Under

Hi I have recently found a skin coloured lump under my right armpit and have recently been to see my gp just over a week ago she examined both breasts and said they felt fine but she did feel the lump and she suggested a cyst I am concerned though has it has not got any smaller but I don't think it has got any bigger could this possibly be a hormonal lump I have had it for about 2-3 weeks?