Super Anxiety out of nowhere at 31 weeks

Angie • I am 33 with a 9 year old and just found out I am pregnant with twins and due July 2016. Terrified and excited all at once.
Is anyone else experiencing anxiety? I feel like I could crawl out of my skin today and have no idea why. Not really anxious about anything other than being super pregnant right now. Lol But just feel super panicky for some reason... hormone related possibly?