During the last week I bought coins and they almost immediately fell by 10-15%, and today early in the morning I saw how they fell by another 15-20%. How long will it last?., and whether I should sell for what I have. I wouldn't want to be left with empty pockets. 
This is indeed a tough year for the crypto market, whether to the point where the bottom is the lowest, it will be difficult to predict.
maybe you should be more patient to see the market recover so that you don't experience a loss maybe in the next year the market will get a fresh breeze to recover.
Every time cannot be a same time and one should be knowing that this is risky yet rewarding . Higher the risk higher could be reward and only if people have surplus amount should be investing in it regularly which will make you wealthy if hold till you get your price