Spots on yellowing leaves

Brown spots on the leaves during flowering can be a sign of Magnesium or Calcium deficiency. To tell them apart, you need to look closely at the spot; if the spots are brown and surrounded by a strong brown edge, it's Calcium (it looks burnt), while if the spots are simply brown and you see yellowish spots between the veins, it's Magnesium. Even if the leaf color is more yellow than normal (it looks like a watering issue), zooming in shows that the area around the veins does take on a more yellowish tone. So, it seems like a Magnesium deficiency. Still, try giving them a bit more water to see if the color of the upper leaves improves. Hope this helps :)