As well as the gentle stretching and exercise you could try some massage therapy or osteo to release the muscles a bit quicker if you need a quick fix.
You could also try heat pads and a nice hot bath with some of the muscle relax soak you can buy (doesn't work wonders but nice and relaxing), I usually stick some dead sea salts in as well and some radox crystals you can get in a box.
Try and relax yourself as might be harder to release muscles generally if you are tensed up - hence why a bath is good too.