Quad Pain

[Thomas Ramsland]

Last Monday I did a set of max reps back squat at 280lbs. My knees were sore and my right IT band was a bit tight before the set. Afterwards they felt fine but I could tell I favored my left side a bit.
The rest of last week my quads felt immediate pain during exercise but not after. So, I rested Thursday, felt okay on Friday so I did some Oly lifting, Saturday the pain came back so I took off Sunday. Monday I felt great. Knees didn't hurt a bit and quads felt good all the way through my workout. I did another set of max reps back squats at 290lbs this time and felt good after. But come tuesday and wednesday my quads hurt during some snatches and cleans.
I rested Thursday and I'm resting again today. I won't be doing max reps on monday but any other ideas why this is happening?
It feels like charlie horses on my quads but I don't hurt anywhere else. It hurts so bad it causes muscle weakness immediately after a set. Could this be caused by lack of hydration, a vitamin deficiency or something that has to do with the lactic acid not getting flushed fast enough?
I am very use to high volume training and have hit a 20-rep back squat at 300lbs before, workout multiple times/day and have never experienced this before. Any help is MUCH appreciated!