I just got achilles tendonitis from overtraining, but i started treating it too late?

I was just at a strenuous four-day camp for color guard that involved a lot of running, pli�s, relev�s, other ballet and dancing, and general strain on my achilles tendon. Two days in, it really started to hurt, and day by day it got worse, but I continued to run on it and relev� (which is when you stand on your toes; that hurt A LOT) etc, basically all day long. Now i'm home, and I finally looked it up to see what could be wrong with my ankle and it is definitely achilles tendonitis. I'm putting ice on it, but should I still walk on it? It is very tense and certain movements evoke unbearable pain. How seriously should I take this "injury"?