i had the same problem with temps this year. big swings in short periods of time. there are others with more experience that can probably give you better ideas, but one question comes to my mind. are the stores of honey in your hive near the cluster?
i had to move mine in toward the middle some. there was plenty of honey in the outside frames, but they were not moving to get at it.
a couple of other things i did: my hives face east, but we had very strong, cold east winds. i closed the hive entrance down to just a very small hole. i left the 1 in vent hole in the top, back, open. when the temp dropped into the teens, i wrapped cardboard around the windward side temporarily.
i have treated with terramycin and will treat for mites as soon as the weather warms. even though our weather now is not great, i have put pollen patty on hive. we are getting enough warm days for bees to be coming out a few times a week, but nothing blooming yet.