Hi Robyn,
It's never too late to follow your passion. A suggestion: Finish your undergrad communications degree while continuing to research the field of social work as well as graduate programs. If you decide that you are interested in pursuing a Master's degree in swk, then know that you will have 2 years of f/t education ahead of you. While researching the field, you can get a better sense by volunteering in a community agency that works with a specific population you might be interested in. If nothing else, this will help build your resume or Graduate school application while give you a sense of being "in the trenches". Having an undergrad degree in communications can always help you in the long run if you pursue social work and should be to your advantage. Most social workers will tell you that you must have interpersonal skills considering that your job will be to work with, and advocate for, under-represented, disadvantaged populations. Good luck!