Right foot swollen at 36w5 days

So to start off I know swelling in pregnancy can be common and normal.Lately my right foot by my three middle toes have been very swollen, and achy and my left foot is completely normal. I can bearly walk on my feet for a few minutes before my right foot starts to swell and ache. I haven’t hurt my foot or anything so this driving me crazy as I have no idea what’s causing it?Has anybody have this happened before? I have a doctors appointment tomorrow of course I would ask her then.