Now we see all altcoins in blood. Why? Everybody sells their altcoins and buy BTC, because SegWit2x is coming. So, don't worry and just #hodl !
The upcoming SegWit2x might be one of the reasons why altcoins are in red color these days. But it is not the only reason. I guess, another reason why this is happening is that there is a particular trend at times that when Bitcoin is bullish, the altcoins will bear the negative effect. They will be on the receiving end of the line. But there is no need to worry about it.