exhaling in water

Why do I have such a hard time exhaling air in the water when the water temps are cold?  It doesn't matter if it is OW or pool, if the water is below 76 or so, I can't exhale out my nose when my face is in the water.  I have no problem with this in OW or pool if the water is warmer. I just keep doing bobs and trying to exhale and warm up, but all that does is cause me pain in the side and bloating.  I practiced swimming all last year at the Rec Ctr. where the water is 85, and then I moved to the college where the water is 78-82.  I had no problem.  I practiced in a lake where the water was around 65 and struggled, but then practiced in a lake where the water was 78, and had no problem.  One of my tris this year was in warm OW, and the other was in very cold water.  I had to swim with my head above water (Tarzan swim) in the cold water, because I couldn't get my breathing down.  Guess I will just have to look for warm water tris.

Any suggestions

jami