nosema or not?

[Rodni73]

One of my hive today have a streaks of bee poop all over the entrance. I will take a picture tomorrow.

My question is why now? they wintered just fine why now in the spring they are exibiting these symptoms?
We had wild temperature fluctuating  in the last week and it rained a lot.  could be weather related stress or
Nosema?


-Rodni