Do you have any pictures? It could be any number of things. Sometimes scale insects get on there and suck the life out of a stem or leaf and cause a spot. Sometimes it's just old leaves that are yellowing up and dying ready to drop off. Sometimes it's some latent winter damage making itself known.. Sometimes it's some sort of fungal infection, etc., which could also be related to root rot (especially if you get a sudden drooping and curling of leaves despite the plant being watered and it being established).

I do have a picture but I'm not quite sure how to post here. I'm new on the boards.

A couple forums have good directions for how to post pictures. Check out this one. It's actually not hard. :-)

When did you plant these camellias?

I planted them 1 1/2 years ago. They've both looked great and bloomed well until this problem recently.