Hindi ko ma-isolate kung yun talaga sa gatas kasi maraming reasons pwedeng bumukol ang underarm, sometimes it's just swollen lymph nodes from stress, hormones, or kahit minor infection lang. Better mag-check ka with your OB or regular doctor para sure, lalo na kung may sakit ka or nag-persist, kasi sila lang makikita ng maayos kung ano talaga yan! But if it's lactation-related irritation lang, make sure ka na comfortable ang latch mo and walang blocked ducts, okay?