As you all know, it was very cold in the Northeast this past weekend.
Saturday, I awoke to find my hot water line frozen. I problem. I
thawed it out with a hair dryer (this happens once or twice during the
winter when it gets below -25 degrees F.) I opened up the hot water
faucet and gradually the drips started and it completely opened up.

Then the water started to back up in the sink. This has never happened
before. I checked for clogs (removing the elbow and it was fine--no
clog just water in it). I pour some hot water down the drain and it
backs up. The pipes leading from the elbow down into the floor seem
fine.

Any idea what might be causing this? Could it be that the faucet
dripped during the night and caused an ice jam down the pipe underneath
the floor? No basement. It is a mobile home.
Your advice is appreciated. -21 F. this a.m.