Based on what you said here, "Partied from Friday until Sunday night and didn’t feed the plants for two days. They were bone dry so I’ve upped water to 1.5 litres every other day. They’re definitely drinking it. Also noticed some golden looking blotches on lower leaves, smaller ones appearing on the next leaves up. Could this have been from letting them dry out or them not getting enough nutrients?"
I'd say she had a toxicity build up due to lack of water. My theory, from observation, goes that if they get too dry, toxins cannot be got rid of by the roots so they go into the part of the plant next up - the oldest stem fan leaves. A good water with clean water (48hrs aired tap water will do) should help clean a lot of toxins out, but the damaged part of the leaf won't recover. The best to look out for is a marked delineation between the damaged part of the leaf and the green healthy part of the leaf. The better the delineation, the healthier the plant has then become imv. After that clean, let her dry (but not too much this time!) then a good ph & ec feed.