Walking Boot for Achilles tendon?

Would i get a walking boot for an Achilles tendon strain? I went to the doctor(sports medicine doctor) about my ankle and he said that i sprained it but i later found out that i had an Achilles tendon strain from my physical therapist when he did a physical examination. I did physical therapy (PT) for 6 weeks and it didn't help and the doctor said that i should be exercising it so i went on a trip where in total i walked 7.5 miles over 4 days. Now my Achilles REALLY hurts. I can barely walk and it even hurts while i'm sitting down. On ehow.com it said that if i had moderate pain i should use crutches for at least 72 hours... So what should i do for it because the r.i.c.e method isn't helping neither is PT.Only people who know what they're talking about answer. please and thank you.