Girls, hello! Could you please tell me I'm very worried, I'm 28 weeks…

Girls, hello! Could you please tell me I'm very worried, I'm 28 weeks pregnant. On Saturday, my little one was actively moving all day and night, he kept kicking, I couldn't sleep normally. Now it's been three days, he's completely quiet. Is this normal? ☹ Maybe I should go for an ultrasound, maybe he got tangled in the umbilical cord, I don't even know what to think about. ?‍♀️ He always felt so tight every day, never like this before, and now it's been three days silent.