Low lying placenta

Alexis • FTM so excited to have our baby boy Nicholas EDD February 2, 2015!
I had my anatomy ultrasound yesterday and little Nicholas' position made it difficult for them to get some good pictures. The chambers of his heart and up his nose and lips. They noticed that my placenta was very low lying and maybe I shouldn't have looked it up but now I'm kind of freaking out. The Dr said no lifting of any kind, no strenuous activity, and I'm guessing no sex also. They also found a white spot on the left side of his brain calling it some kind of cyst I can't remember because I was kind of in shock and that I could get the chromosome test done to ease our mind that he is ok. My husband has a broken spine that is congenital both his brothers also have it and he's worried he might have it now too so we are thinking about getting that test done. Any stories, experiences, helpful advice or words of wisdom would be great!