Soleus injury help

Have an injury question, My calf (mostly my right) soleus muscle gets really sore and tight and almost knotted after I've run about 3 to 4 miles. I have been using compression for it and have had some PT and I'm icing it and rolling it with foam roller and tennis/golf ball. I'm just wondering why my soleus and if anyone else has had this issue and if so, what was it caused by and what was the resolution? Thought maybe some of the runners in the group might have dealt with this before. I'm close to going to the sports doc just because it's really frustrating. Thanks
Lynn