Is it possible to have a soleus injury that a mri or us just won't detect for some odd reason? if that is the case, what might be the next step?

Soleus pain: Muscle pain in the lower extremity may not be due to a problem within the muscle itself. In some instances the physician needs to assess that the problem may be extending from a nerve root that innervates the soleus muscle. EMG and NCV studies can help rule out these problems. A neurologist can evaluate and request these studies. Good luck.