Indecisive test reaults

So I scheduled an appointment with the obgyn because of a lump I found in my breast, they are also very itchy and sore. She did an exam and told me it feels like a fibrocystic knot and it should be nothing to worry about. She did say she wanted to do some blood work. They call me and my hcg level is 3.8. She said these are indecisive results and I have to come back next week for more. I had a miscarriage in July 2016 and my hcg level was below 1 in August last year. What would cause them to rise? Any advise?