If so then I can help.
Quick bit of Anatomy
Sandwiched between your lower back and the top of your legs you have your pelvis. For simplicity sake imagine this is a square box. The muscles running up the back of your upper legs (hamstrings) are attached to the bottom back part of the box. The muscles running up the front of your thighs (quads) are attached to the bottom front part of the box.
Our abs attach to the top front part of the box and our spine attaches to the top back part.
All four of these connections have an influence on the movement and stabilisation of the spine.
Fixing Tight Hamstrings
If you suffer from tight hamstrings then stretching them may NOT be the answer.
More often than not people have overactive Quads (thighs) because they don't use their buttocks enough.
Shorter and overactive quads will pull on both the knee cap and also the bottom front part of the pelvis. The pelvis will tilt forwards slightly lengthening the hamstrings at the back and giving the impression that they are tight.
The solution: stretch your quads and strengthen your hamstrings. If you were to stretch your hamstrings you are then allowing more slack for the quads to take in and so the problem worsens. Modified Floor Block Hamstring Curls with abduction are a great hamstring strengthening exercise.
Fixing Lower Back Ache
If you now look at the top of the pelvis you can see how the tight quads and forward leaning pelvis effects the lower back. As the pelvis leans forwards the back muscles shorten and the ab muscles lengthen. If you have ever seen anyone with an excessive arch in their lower back (lordosis) this is usually due to a forward leaning pelvis. This excess curve in the lower back puts extra strain on the lower spine and usually causes back ache. The solution: strengthen the abs. A good exercise are static back crunches.
The pelvis is at the center of most movement. There must be a nice balance between the hamstrings, quads, abs and back. Most clients I work with need to strengthen their abs, stretch their quads and strengthen their hamstrings.
Spend some time doing this and I'm sure your tight hamstrings and lower back ache with disappear.