It is not good to short some stock like this. Basically, this is a crazy market. The more expensive the stock become, the more it will go up. Especially when it still is going up today. Just look at what was goin on with BCOV, DWRE, GWRE, YELP last few days. Those guys simply do not care how high they can push those stock, thise big institutions can get out whenever they feel like to do so.
Small investors are all on those guys mercy. The only thing you can do is joining them and get out ASAP whenever you feel those big sharks decide to get out.