Roots are suffocating from over watering. Thats causing the drooping, and necrosis spots and curing leaves. Weed likes soil on the dry side. Roots need oxygen. When the space is filled with water, there is not room for oxygen for the roots and they suffocate. Wet roots also have a rusk of root rot. Stop watering it so hard. It's small it doesn't have a big root ball to suck it up.