Bittrex was holding that position. Now the users can dump BCH.

Bittrex users? Their BCH has already been dumped, and they have been credited with BTC equivalent of the value of BCH. That's fair game, one way out of four to handle such a fork (the other three being to ignore the fork, credit the user with their BCH and to sell the BCH without crediting the users. The latter can arguably be classified as "theft")

Many "smallblockers" were dumping their BCH right after the fork. Bittrex was holding quite much BCH and has been quite late in the game dumping it. Their dumping of BCH has for sure caused quite much supply of BCH in the market. Price goes down with supply and up with demand - if the demand is constant and Bittrex stops dumping BCH, of course that will push the price of the BCH upwards.

I'm fairly bad at predicting the future, of course there are many other things influencing the market price, of course the assumption that the demand will stay constant is just an assumption. I wouldn't be surprised if the price will continue slumping.