Sour crop????

My young poullet has been drinking lots of water since I got her and I began to notice she would dribble some out after drinking (quite a bit) and she also began to have really watery droppings. Her crop has felt like a water balloon and I drained it a couple of weeks ago (she then seemed fine but would then have watery droppings and dribble after drinking again). Today she is lethargic. Is this sour crop? How can I treat her?? I lost my first chicken last year and would hate it if she passed 😞