Yellow leaves on the Golden Midget

The leaves on my Golden Midget watermelon plant are starting to turn yellow faster now. The oldest leaves are a pure pale yellow and some have started to turn brown and die. The plant puts out a few male flowers every day but very few females. And the female flowers wither and fall before opening. The one melon on the plant is still growing and is now the size of a really large grapefruit. But it hasn't started to turn yellow yet, like it's suppose to.

Golden Midget watermelon plants have been known to turn yellow but I'm not convinced that's what is happening to my plant. I started adding ferts to the water over a week ago. Just general purpose water soluble crystals. But it doesn't appear to be slowing the spread. It almost looks like a spider mite infestation but I can't find any anywhere. It's got to be a nutrient deficiency. Or maybe over-watering. It's in a self watering container and I've never had problems with it before but who knows. Maybe it's getting more water than it wants. I suppose it could also be a virus of some kind but more likely something simple, like a lack of nitrogen. I suspect the plant will be dead before that melon is ready to pick.