I'm fairly new to running, managed my first 30 min non-stop stint about 3 weeks ago having built up to it gradually over the past few months. I have been doing the 30 min run about 3 times a week since and everything was going fine until this morning. When I was about twenty minutes into my run I felt a niggling pain in my left heel. I continued running but had to stop after about another five minutes due to the pain. I did all of my stretches and walked home on the foot fine afterwards. But since getting home the pain in my heel has gotren alot worse. It's fine when I'm sitting but when I stand up I cannot walk flat on the foot as a sharp pain shoots through the heel each time. Does this sound like Achilles tendinitis and if so what can I do to make walking on the foot a bit easier?