It's just a price display error. I get that a lot of times. In fact, it is very unpleasant when you see that your portfolio has grown to $ 10,000 in a few minutes, and then again dropped to $340 
Sad
There are some coins that are showing the same error like what has already received by OP. Remember just like there was a coin that has very low volume and it can be pumped easily to create a manipulation on its price. SadThis just a usual problem need to be fixed.