My sciatica (and most of my former clients) had it mostly from lower back, across buttock/hip flexors, and down the side of the leg. When really bad, it goes all the way to the toes. It feels a bit like electric shocks and stabbing pains at the same time.
In saying that, I was taught during my diploma that sciatica can sometimes be experienced down the front of the leg too. But more than likely, how strained a muscle. Did you sort of do the 'splits' when you slipped? ie: i leg slid forward more? if so, I would assume that it was the leg that stayed back that is now painful.
Rest, ice (up until 72hrs after accident) and then heat and epsom salts baths can help. Local anti-inflammatory cream can also be good. But as masma pointed out, there could be other causes worth investigating.
Good luck!