Don’t take this to heart and think it’s you’re fault. I think you should talk to him about it. As this could be many things, like he might have something on his mind or over thinking. Or you can start at the basics, like try more foreplay with him.
You shouldn’t be self conscious about you’re body at all! But it is easier said, than done. I know everyone says it but, your boyfriend should love you for you. But their is another option, you can always have a mole removed by a doctor. But that is entirely up to you, and what you feel more comfortable with.