mel dont be too hard on yourself, we all have off weeks for various reasons, you expected to gain weight, i know not as much as you have, but still dont be hard on yourself.
It is very hard to keep motivated if you let yourself give in to depression about the weight gain. and remember even though you may have gained weight, your body shape may have changed.
congratulations on the 5k run, that is excellent, keep up the great gym work, and you will lose your gain in no time.
hugs angel