This happened to me and I ended up having mastitis. I’d go to your dr and have them look check it out.
This happened to me and it was a milk bleb https://my.clevelandclinic.org/health/diseases/24166-milk-bleb whatever it is, probably worth having it checked
I have this exact same problem!!! I spoke to my midwife it’s normal she even looked and saw he’s latching correctly I think it’s just because they prefer that side! Maybe ask a midwife or health visitor to watch and check babies latch is correct on that side