As someone who has worked on people with back problems for 27 years, who has had a fractured vertebra slide 75% forward, and continues to have sciatic pain I would like to put my 2 cents in.
Before going in to ideas which can help a sore back, I would like to mention that back pain can come from referred pain from your organs or glands; Other more serious health issues can also cause back pain and make you feel like doing nothing. It is a good idea to go get a check up & at least get an X-ray done.
Doing some of the exercises mentioned, which do help a weak back, can cause further harm if you have a hairline fracture in a vertebra or hip.
If you have not fallen, lifted something heavy, lifted something heavy and twisted, jumped down from a tall vehicle or something high, been in any kind of accident - even a couple of years ago, etc....read on.
1. Most suggestions in this thread are great! I did add to a couple of them.
2. When you sit, you are balancing on your tailbone, so if a harder chair causes more issues for you it may indicate you are having an issue with the complications of doing that. The joint where your sacrum (Tailbone) and your illium (hip bone) meet can be a source of back & hip pain. This area can shift when you fall or lift something heavy and twist (Think Sam's Club, or putting the kids in a car seat). The sciatic nerve goes through this area and can be pinched.
3. Stretching too far forward with your arms, or grabbing a railing while falling down the stairs can cause lower back pain because the Lattisimus dorsi (Largest lower back muscle) attaches all along the top of the hip bone, up your spine to mid back, stretches up from both those area to your side, and attaches to the front of your upper arm. Extreme stretching of this muscle with your arm outstretched can cause lower back problems and can pinch the sciatic nerve which comes off several places along the spine. It can hike your hip up on one side...do your pants seem longer on one side?
4. I often find certain joined muscles, Ileo psoas, which attach to the inside front of the hip bone, down to your inner upper leg, and up to your lumbar spine in several places can cause similar back pain & hip pain. Releasing these muscles can be difficult and some people are brutal when they do it, which is totally uncalled for. There are several stretches which do help.
5. I find stretching and pressure points to be the best method for my body to relax and let go.
6. I go by the following: ICE when you have a fresh injury (Think of the ball players who put their body in ice at the game or after an injury), or ice when there is further irritation, inflammation (Hot and or red looking), and swelling. Use HEAT to increase circulation, and it is really great to use before doing stretches (Think of how taffy stretches when it is warm).
7. I recommend using tennis balls (Used are best because they are more pliable). See my prior post in the thread to see how they are best used for the back.
8. Many topical lotions, gels, creams, etc. are helpful. I use Olba's oil (A blend of essential oils which smell like Vick's Vapor Rub & does clear your sinuses out really well) which sinks in very well and will either cool down or heat up depending on what your body needs. Icy Hot is similar. I just like using natural items rather than chemical when ever I can.
Good luck with your issue & hope you feel better soon!