I came off diclofenac two days ago after taking it daily for a month. I'm swollen and can hardly fit into my usual clothes. How long until this stops?

Fluid retention? And certainly can't fit into your clothes. Are you telling me your swollen. Are your leg swollen? Are you trying to get in skinny jeans? The Diclofenac can possibly hold on the fluid, but you need to report to your physician.