15w5d...suddenly exhausted

Lauren
So I'll hit my 16week mark on Sunday. I FINALLY started feeling better probably around 13.5weeks but all of a sudden I feel like my energy is ZAPPED completely as of yesterday evening. I've been noticing more round ligament pains too with sudden movement the past day or so and some mild to moderate aches and pains. This is baby number two and I can remember feeling similar around this time with my first but I can't EXACTLY remember if it was now or earlier or later. Anyways, I just feel gross...like the flu without the nausea and vomiting. Mild body aches in my back and hips. But mainly it's the exhaustion which has been SO much better until all of a sudden. Anyone else? I'm guessing it's just a growth spurt but I'd love to hear from other early second trimester mommy to be's who feel this sudden change