I've got pretty lumpy breasts normally especially pre menstrual.
Due on in two days and breast are sore (normal) so must have been rubbing one as I took off my bra and felt a lump.
It's hard to distinguish from generally lumpiness, but I think I can feel it.
Would you see GP or wait until period is over to see if it goes. Don't want to waste the GPs time especially at the moment