3-4 days of active fermentation is somewhat normal, so it might be temp related. After that, the yeasties still do things, just not as crazy like and it's not as visible.
Also remember, fermentation is an exothermic reaction (gives off heat), so the wort/beer is typically warmer than ambient. I would suggest one of those sticky fermometers...not the most accurate thing in the world, but it's better than nothing/guessing. I find that I'm usually between 2-6 degrees higher than ambient temps.
When it gets that cold, it definitely can affect the yeast's ability to do their work...but that often depends on the strain of yeast. (Some do all right in cooler temps, even ale yeasts.) It probably would benefit from being moved to a slightly warmer location....perhaps not to 70 degrees, but maybe a chilly bathroom or other room with an exterior wall? You may want to try lagering in the winter, or at least use ale yeast that is known to perform OK in the 50's on future batches.