my belly went big and THAN shrunk?

Ashley • Single mommy to a baby that's still in my belly💕☺️
So I'm about 13 weeks. My stomach got HUGE but than all of a sudden it shrank completely and looks flat. I've been told it's because my stomach was bloated and now it's going to actually be baby growing once it gets bigger? Should I be concerned? I have no cramping or blood.