It's been a while since I grew squash, but this sounds like squash vine borer to me. GG?
Our squash plants look pretty bad. Practically overnight the stalks and the leaves went from looking good to completely droopy. I've been trying hard to keep them watered without overwatering. Unfortunately, I'm just the substitute gardener while N is away so I don't really know what I'm doing.
Hard to say. I've not yet had to deal with squash vine borer, but it seems to me they'd take down one stretch of vine at a time, not all the plants overnight. More likely drought stress or some kind of virus (which can be insect-borne, most likely by cucumber beetles). I have to say that, in 25 years of vegetable gardening here in Vermont, I've seen a dumbfounding uptick in the number and variety of insect pests in the last 5 or 6 years. I think a lot of that has to do with the milder winters. When the ground freezes solid 4 feet deep for 4 or 5 months, there's not much that can survive in it. That doesn't happen much any more, so eggs for all kinds of plant-eating bastards hang out all cozy in the dirt and then hatch just in time to fuck up the garden.