Brief Answer:
Here are some suggestions:

Detailed Answer:
Hello and welcome,

I am sorry you injured your low back. Although cold is usually recommended in the early phase of a healing injury because it helps to decrease inflammation, if you are having muscle spasms, use heat. Moist heat is most effective, but any heat will be helpful. A heating pad will help. If you don't have that, even a hot water bottle wrapped in a thin cloth might help. Don't fall asleep with a heating pad on as you can sustain burns that way.

If you can tolerate NSAIDs (non steroidal anti inflammatory medicines) such as ibuprofen, that might work better than Tylenol. Ibuprofen, in addition to decreasing pain (which Tylenol also does) will decrease inflammation. You can take it 3x/day. Make sure to take it after you have some food in your stomach so that it doesn't irritate your stomach. Contraindications to taking NSAIDs are a history of stomach problems, kidney deficiency, or bleeding abnormalities.

Rest as much as possible - preferably in bed and with something under your knees to support them which will decrease stress on your low back.

If the spasm becomes severe, you may need a muscle relaxer such as Flexeril (cyclobenzaprine). Some people don't like Flexeril or other muscle relaxers as they can knock you out. But taken for a short while they can be helpful.

If you start to have any symptoms of nerve impingement such as numbness or weakness in your legs, then go in to see a doctor immediately.

After having a low back injury where one's muscles tighten up, sometimes there can also be constipation, so eat plenty of fruit (consider prunes if necessary) and if constipation becomes a problem, take a stool softener such as dulcolax.

Please let me know if I can provide further information or clarification. I hope you are feeling better soon.

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