Sick- low immune system

Angie
It's usually rare for me to get sick. However, I'm now sick for the second time within two weeks. I have terrible body aches and headaches that I'm assuming is a cold this time, last time it was a stomach bug. 
Anyone else getting sick often since being pregnant? What are you doing to increase your immune system? I eat plenty of foods containing vitamin c so I'm not sure what else to do.