Hi,
This trend is logical. You will see many posts about it, many people will tell you to sell. Don't sell. Just wait. Or buy if you can.
This is the "normal" trend. As in December, prices tend to rise, in January, they generally go down. More or less sharply, that's right, but still the trend is logical.
I am convinced that by Dec 2018, prices will reach new all-time records. This is of course only my personnal opinion and I cannot say this will happen for sure. But I'm pretty convinced it will