Doctor time. It could be nothing. It could also be toxemia, preeclampsia, gestational diabetes, lymph system issues (the lymph system is what cycles all the fluid that is not blood around in your body)... gosh... any of 100 things can be an underlying cause of edema.
I was also a health nut when I got pregnant (ummm... a little too much, female-athlete-triad anorexia and pregnancy cause some really bizarre results... I didn't LOOK anorexic, I didn't ACT anorexic, but I just consistently didn't give my body the calories and nutrients it was burning. i SHOULD have been consuming apx 4000 to 6000 calories per MEAL for the training I was doing... but wasn't, instead I was getting that per day). And ended up with a bizarre medical thing (see above) that shut down my metabolism with the baby... (read gained apx 20lbs per month until kiddo's totally healthy birth, aka gained slightly over 185 lbs)... but I ended up slammed into bedrest in my first trimester. And on a 2100 cal per day diet for doing nothing but lieing and sitting around, with over 100 grams of that being protein and enough calcium to make a cow look at a glass of milk in the face and cringe. But my bones needed ca++ and my baby was GROWING bones.. so there you have it. LOL... I ALSO lost 40lbs the day he was born... and another 30 over the first week (just peeing and peeing and peeing). So a LOT of that weight was edema / swelling. Actually, my first symptom was edema. Hellooooo "cankles".
Is this you? Probably not. But weird things happen when we're preggers... and I just sharing to show that even athletes have weird things happen. I couldn't have been MORE healthy appearance and lifestyle wise... but it was just that that did me in. My 10lb 23" gorgeous baby boy was born completely healthy and normally.
So ... doctor time girlie.