Hi.
Brown leaves: Could be a sign of phosphorus, potassium, magnesium, sulphur, manganese deficiency. Could also be nutrient burn (more solid brown colouring) or heat stress (brown on the edges)
Leaves droop: Could be a sign of overwatering
Leaves curl downwards: Could be a sign of potassium or phosphorus deficiency, or overwatering
Maybe this will help.
Luck