I've researched a little regarding a correlation between BTC and other assets but could not find anything specific. In general, It may be trading opposite of the USD index...

Finding buying opportunities depends on the hodL'ing time frame. Watch the stochastics indicator and when it is under the 20 level on a daily chart which is the 'oversold' area. Once both lines (K and D) are over 20, the trend tends to continue to the upside and often to the overbought area which is over 80.

I speculate that the bottom for 2018 was on Feb 6th.