Milk supply

From the day I had my son, my colostrum was really really good, my milk came in great.. just a couple days ago as I was feeding him my other side leaked so much it covered the pillow I didn’t even notice. I could pump about 4oz in 20 mins or less. Now I barley have anything. I’m having to basically milk myself while he eats to push it out. I was bad about drinking water the other day but I wouldn’t think that would make it go down thaaaat much. I am drinking a ton of water and trying to pump a lot so my body will realize it needs to make more. Is there anything else I can do to boost it? And does anyone know why it would significantly drop like that? TIA