Lump in armpit - cyclical?

[Cornishbelle]

I've had a large pea sized lump in my left armpit that has come and gone for some time now- I have taken antibiotics as recommended by Dr but it has now come back again. Noticed I have flu like symptoms when it appears and seems to be around the start of my period too.

Has anyone had this before? I'm waiting for the Dr to get back to me but just wondering if this sounds familiar. I'm 44 for context periods have become more regular over recent years (have pcos) now lighter but were really heavy, plenty of peri symptoms too night sweats at start of period, brain fog, exhausted no libido

Had blood tests earlier in year Dr not convinced peri

The doctor should refer you to the breast clinic for an ultrasound.

Period "flu" is definitely a thing and it could be that your lymph nodes are just reacting to that. Has a doctor actually palpated it properly?

I've got an appointment for three weeks time. I started period yesterday and already today the lump is shrinking again so probably by the time I go it will not be able to be felt. Feel glands in my throat and back too definitely feels fluey