Hi. went and had ultrasound today on left breast and underarm. said lymph nudes 3 cm. normal size ? hurt

Reactive?: Enlarged, painful lymph nodes can be seen if there is an infection in the region which they drain; they are referred to as reactive if this is the case. In general, axillary/arm pit lymph nodes can become fairly large and still be considered within normal limits; their shape and morphology are better predictors of benign vs malignant nature.