I am about 3 weeks pregnant and have been experiencing a achey left arm, left shoulder, and left side are these symptoms of early pregnancy?

Not typical in pgy. If you have persistent, unexplained left arm and shoulder pain, you should be seen by a doctor. If you have any cardiac symptoms, like chest pressure or dizziness, go ASAP to ER or Urgent Care.
3wks pregnant + pain. 3 weeks pregnancy should not normally cause you arm or shoulder pain. Left pelvic discomfort may be due to a cyst from the egg from which you got pregnant. Please have yourself checked to make sure that you do not have ectopic pregnancy or other problem. Good luck.