Arm weakness / 5 weeks

Hey guys, so i’m 5 weeks and 3 days and my left arm has been feeling like weak for the past week and a half. it’s like it feels heavy when i pick it up. first it was shoulder pain but it’s not i’m my shoulder anymore. My neck sometimes feels uncomfortable as well. My doctors says long as my hcg levels are doubling im good which they are. Has anyone else experienced this?