I Am Sure That I Had A Cyst On My

I am sure that I had a cyst on my Soleus tendon which until yesterday was benign and gave me no problems. It hadn't changed size/shape since I noticed it - it was in the area at the top of a 'normal sock'. Yesterday I completed a marathon and the area is now incredibly tender and warm to touch and although the lump is still there I think it has reduced in size. Could this cyst have burst? if so what should the treatment be?