How do you manage soreness?

I am about to hit 50 classes on Saturday (yay!) but I have had to scale back to only going three times a week, (when I first started I’d do 4 or 5 times). I’m feeling extra sore lately, especially my back in bed at night and my knees. Do you think it’s a form issue or just regular workout soreness? I’m finding it hard to tell. Any advice or suggestion for post workout care? I do try to eat a protein heavy snack after and drink enough water.