Having breast tenderness/fullness and a greasy/whitish yellow and clear discharge. should i be concerned? 9 months after weaning my son.

Mastitis: What you describe sounds very much like mastitis, an infection of the milk-producing glands of the breast. This is common while breast-feeding but can happen anytime. It often resolves with anti-inflammatories (ibuprofen) and frequent warm compresses, but an evaluation for an abscess is necessary to make sure there's not an infectious pocket that needs to be drained or need of antibiotics.