Aww sayang, don't worry la, cysts during early pregnancy are quite common and usually nothing serious, especially at 5 weeks. A few of my mum friends had the same thing and their doctors said it was okay; sometimes they resolve on their own as pregnancy progresses. The best thing is to follow up with your doctor or gynae to monitor it, just untuk peace of mind, they'll do another scan later to check how it's going. Sending you lots of baby dust, everything will be fine!