I will have to disagree with Bob on this one; I am not aware of any nursing bottle in this shape.
The shape is reminiscent of Sandwich Glass cologne bottles so that is my first guess. However, the lip, color and shape also suggest a miniature food or sauce bottle; the more I reflect on this bottle, that is emerging as my best answer.
Lastly, that blue-green color was infrequently used for druggist bottles, although I highly doubt the use was for medicine.