It seems that people want to find a reason for everything going down currently. However, there probably isn't any specific reason for it. Market act in a random manner, but they always tend to go in the correct direction. That being said, what we are currently seeing is in part because some people are panicking and getting out and partly because the prices have been going up too fast. This will probably balance out in few days if not by tomorrow already.
I wrote a post about why it doesn't matter if the market is in a bubble a few days ago, please have a read about it if you are afraid of the apparent crash or that it might continue:
I can't tell you if the market will still go down, but this is a good point to revisit the reasons you invested in the currencies you invested in. If you invested in them because you wanted to make a quick profit but didn't do any research on them, well now is a good time to do the research. If the market crashes some of the worse coins might die, this is good. The stronger coins will survive and will be stronger after it. If you invest in the coins that actually matter, you will be fine. However if most of your investments are below the say top 200 coins, then you probably really want to consider why you invested in them. Maybe there are some gems there, but most likely most of them will be dead eventually.
The best thing about the current situation is, that you get to buy what you want. Everything is cheap now, except bad currencies, but you shouldn't invest in them anyway. So if you've been considering buying something, now is your opportunity! Just make sure you're not buying it because you saw the price spike and thought that maybe it will spike again. Yeah it might, but it needs to be a good currency also.
Finally, relax. Judging how cryptocurrencies seem to work, this correction will be over in no time. In no time in my terms is within a month, but probably much much faster. This is where you get to test your ability to hold over unexpected news, which is one of the most important skills in investing, not to panic. Keep true to what you believe in.