If one ankle were swollen I'd look to AS as the culprit, it usually affects peripheral joints asymetrically (RA affects joings symetrically). Sounds like water retention. Meds can cause this. Also check your BP, could be a relationship there too. You could try an over the counter diuretic (Pamprin is one) and see if that helps, so long as you check the label for any adverse drug interactions with, say, an NSAID that you're on.
Cheryl

My guy
Life is not measured by the number of breaths we take, but by the moments that take our breath away. George Carlin

Dogs mean it when they kiss you