why I'm running out of milk !

Sindhu
Sometimes I have looots of milk sometimes I have nooo milk. Tonight  I had NOO milk and LO cried his eyes out !  What do I do im exclusively breastfeeding I practically had him sleep on a pillow and squeezed some milk into his mouth then he stopped crying. I had to squeeze so hard that I could get some drops in. I've never had this before.... what do I do !!??