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. 
Selling crypto when the price falls sharply is the worst idea. Because, besides making you suffer losses, you also contribute to the falling crypto prices that you have today. You have to think positively, be big-hearted, and believe, that crypto prices will not forever fall, he will surely rise and head towards recovery.