Welcome to Health Care Magic
Thanks for your query
Well with the limited history provided by you , the node you mentioned might be Axillary Lymph Node , these group of lymphnodes
my be increased in size either due to some infection or there are variety of other causes are localized infection, possibly somewhere in the arm or breast draining into the glands of the armpit, or infection within the armpit itself , cat scratch disease
, ascending lymphangitis
, lymphangitis .
the best way to rule out the cause is go for a FNAC to a cytopathologist this is the cheapest way to diagnose your condition as this procedure is minimally invasive and least painful and rapid diagnosis can be made .
once the diagnosis is confirmed it can be managed accordingly .
unlikely in your condition it is associated with menopause
Wishing you speedy recovery , All the best .