Your saddle position is not set based on distance from the bars, it is positioned in relation to your BB and pedal stroke. The distance from saddle to bars is determined by your top tube length and stem length. If your saddle is in good position relative to your pedal stroke, don't move it back just to get a couple more cm to the bar. Get a longer stem. Also consider your stem height and angle. If you have lost some flexibility and core strength and/or gained a few pounds over winter you might actually have to raise your bars a bit by changing your stack or flipping your stem until you get stretched back out. Yeah, the "slam that stem" crowd will get their chamois in a bunch over that last statement, but you have to ride what is comfortable, not what looks cool. Do some lower back and ham stretches and core strengthening exercises to limber things up and keep them in place.
Make sure you are rotating your pelvis forward rather than hunching you lower back to get aero as well. If the pain persists, gets worse, or the pain down your legs increases or your legs start to tingle or get numb, see a doctor to make sure you don't have a disk problem impinging nerves.