Bitcoin is going down very hard till now after touch ATH last year. Any idea what caused it? And what the impact to other altcoins? Any opinion when bitcoin will be rise up again? 
There are many reasons for this. Since Bitcoin gained so much popularity some people started using it for scams and frauds. This led to the interference of government. Many governments also gave their negative views on Bitcoin, which made people skeptical and they started selling it. But this is just a temporary phase. Owing to the fact that Bitcoin still has the faith of many investors, its price will rise soon.