I had back issues that started a little over a year ago and got really bad around late April of this year. It turned out I had a couple of herniated discs. I got treatment for them in May and have been pretty solid ever since, despite not being able to fit my yoga classes in due to changes in the studio's schedule. Stretching is a really good idea, but you might want to get checked out first because stretching if there is some actual injury could make it worse.
One thing to be aware of, though, if you do find you need treatments: make sure you check your health coverage before doing anything that involves an element of pain management. My payer (NJ BCBS) just changed their coverage levels and because of that, if I were to get those same back treatments today, I wouldn't be covered for the anesthesia. That's kind of ridiculous because the procedure itself involves threading a very large needle into a very specific spot in your spinal column and if you can't be knocked out while getting it, you're pretty likely to move from the excruciating pain (I've had a needle stuck in my back without being knocked out before and it is really painful.) But it's not covered anymore because the payer is trying to incent doctors to do these procedures in their own offices since it's much cheaper for the payer from a total medical outlay perspective that way (no OR fees, no post-op care, etc.) They're even paying the doctors a lot more if it's done in the office vs. in an outpatient surgery center. So, anyway, just something to be aware of if your back issues turn out to be something bigger than flexibility concerns.
