The answer to your question depends on a few factors. Most nutrition consultations that are done in the clinical world are done for medical reasons. For example, a nutrition consultation can be done if someone has been trying to lose weight, but has not been successful. Cancer patients often have a hard time keeping weight on and a nutrition consult can help them find ways to consume more calories. Diabetics often need help choosing foods that will help control their blood sugar. In your case, It sounds like you are working out, but not gaining any muscle mass because you aren't consuming enough calories. Muscles become larger only when there is sufficient protein left over after your body has the energy it needs. Thus, while I don't think that a nutrition consult is needed emergently, it may help you in figuring out your diet to best fit your goals.
I suggest that you schedule an appointment with your primary care physician
or internal medicine doctor). He or she can help you understand how to best achieve your goals. If your doctor feels that you need more nutrition education, then you may get a referral to see a nutritionist
in a separate visit.