Brown discharge at 34 weeks?

Experiencing light brown discharge (had one decent size clot) went to the hospital they did a pelvic exam and US, stated that my cervix is closed but my placenta is close to my cervix. Have a follow up at my doctors in a couple days but I am just wondering how worried should I be and what can cause my placenta to continue to get closer to my cervix? This is my second baby but I’ve never experience something like this. I have only had two US since finding out I was pregnant and the last one I had before this was back in April. I am due at the end of August! Any advice/knowledge on this topic is gratefully appreciated :)