Liquid plumber

The drain in my shower has stopped working. Well it works a little bit but it backs up very fast. 5 min into your shower you are standing in 6" of water. This is bad because my shower is only 7" deep. If you know strange facts about me you know i like to take 20 min showers. these two fact contradict each other, I haven't been too happy because my relaxing showers have been cut short. Of course we don't have any products that could fix this clog and i don't have a car to go get it.