I was always told by medical people to ice it for the first few days, then change to heat to help the healing process. Anti-inflammatories like Ibuprofen help too. Good luck. :)
Ice and compression for first 48 - 72 hours
Some people don't tolerate ice well, especially on your back...but if you do tolerate it well like I do...ice is definitely your friend in the beginning because it helps reduce inflammation. I lay on an ice pack because that way I get a certain amount of compression too. Heat after that time period will help loosening up the back muscles and help the healing process
I'd recommend ibuprofen, a warm bath, and massaging the area very gently. Also, walking is good, but try to keep bending down and rotation of your back to a minimum. One of the best things you can do is just lie down for a while.
A long hot bath, and keep walking which may help.
Ibuprofen for the inflammation at about 600mg every 5-6 hours. Do the old tried and true lower back pressure relieving thing. Lay on the floor flat on your back. Place a chair under legs at the knees. DO NOT stretch. That is the last thing you need with a pulled muscle. That position takes the pressure off the lower back.
Warm baths help back muscles. Well they work on me.
Capsaicin pills or hot peppers or hot pepper pain cream.
Stretching and icepack. But do not ice lower back.
I'm curious. Why don't you ice the lower back?
If you have low back pain, you almost always need heat instead of ice.