When I started the programme had no problem with my muscles being sore or hurting. Have done 3 runs using a interval training programme, so have been pushing myself and my muscles have been a little sorer. Today decided to just go out for a 3k run and see if my speed had improved but my right muscle (the one above your achilles) started to hurt and eventually I ended up walking after 2.5 miles. I stretched out but can hardly walk now. What is the best thing I can do?