Hello, and thanks for your question. It's unclear what's causing this sensation for you. There can be fluid after a breast reduction, which is normal to some extent. It is unusual to have so much fluid that you could hear it with motion, but it could be that it is a different sensation that feels as though there is fluid. Overall, it's just difficult to say without an exam, so I would recommend that you see your surgeon so he/she can examine you. Things to be immediately concerned about would be if the breasts are increasing in size and getting very tight and/or red. This is especially concerning if it is only happening to one side, as that could indicate an expanding collection of fluid. Otherwise, swelling overall and some redness around incisions is normal. I wish you the best in healing.