A normal cycle in the market, most of the time altcoin price one step behind bitcoin or depends on the market dominance, the trend in the market, some coins may increase higher than bitcoin (in percentage). However, bitcoin price does affect altcoin prices as a result or effect that makes it vulnerable to market sentiment.
The best time to sell altcoins may have passed, and now is the opportunity to wait for lower prices to buy back and wait for the next rising wave if the bullish trend is still going to continue which is predicted in August until the end of the year, just be patient.