Right on, too much feed for the amount of light, and unless you are in a warm-winter area, it probably gets COLD in front of those windows at night.
Check the cabinet growing section for some cheap and simple grow chamber ideas that will perk them back up again, and see what you can do about a better quality fertilizer than MG.
Pretty soon, you will need to give a heavy watering with tap water until it runs out the bottom of the pot, then water some MORE, but I'm concerned that with cool temps and low light you will have a hard time flushing correctly because the soil sits wetter for longer under your type of conditions.