You have to understand something here.
Bitcoin is in the market so its price depends on supply and demand, like in every other market in the world.
So, if more people buying, price is going up.
If more people selling, price is going down.
There is no mystery here but also no reason for panic.
It's normal situation and it's happening all the time.
Now, price is going down, in a several weeks will go again up and so on.
I suggest you not to look BTC price to often, and worry to much about it, but to concentrate on collecting as much Bitcoin as you can get