1) Don't do incline activities (for a while). After a few weeks see if the issue resolves itself.
2) Depending on the severity and duration of this pain, think about seeing a qualified rehab clinician. How tight is your low back? Do a standing back-bend and see if that produces a similar pain. I bet you are tight and that it will. But it may be wise to find out what it is before you keep exercising with offending movements.
3) Try light stretching, yoga, or a heat to your back. This may loosen and relax it a bit if you don't do anything too extreme.