They're not torn, they're inflamed. If they were torn you wouldn't be walking. Inflammation can come from anything...medication, diet, being overweight, wearing bad shoes, hormonal changes, etc.
I had achilles tendonitis and plantar fasciitis at the same time a few years ago. I put off treatment for months and just when I resigned myself to making an appointment to be checked out , I just happened to ask for new running shoes for Christmas and got fitted for them at a running shoe store (Marathon Sports). Turns out that my other running shoes were 1/2 a size too small and the wrong structure. The right shoes provided almost immediate relief from the pain and even without the shoes on (barefoot, in sandals, dress shoes, heels, etc.) I haven't had a recurrence of the pain.
You should be seen by a doc to make sure that you're not at risk for a tear due to strain or inflammation, and she or he can recommend stretches and other remedies. You may need an anti-inflammatory course of ibuprofen for a while to get the inflammation to calm down and give the tendon time to heal, or you can try some natural anti-inflammatories if you know someone who you trust who can recommend the right products.