need advice

so my husband and I got married back in September but before we got married we had issues in the bedroom and still do. He never wants to have sex. only when its convenient for him it seems. I'm lucky if I get it once a month. I still love him anyway and there are no signs of cheating but I'm so sexually frustrated I dont know what to do. When I get in the mood (which tends to be often) he denies me. I confronted him about it and his response was " I dont know whats wrong with me okay!" what should I do? It's really frustrating.