hey TC
There is a product in Australia called called PainAway spray. I'm not into homeopathic medicine at all as a rule but I picked up a bottle of this on special once and when my back was severely spasming from a similar injury I tried it in desperation and it really helped, and has helped since.
Obviously it's not available internationally but all it is is a mix of oils etc -Arnica Montana Flower Tincture, Rosemary Oil, Boswellia Carterii Extract, Eucalyptus Oil.Also contains Lavender Oil, Jojoba Oil, Vitamin E..
It might be worth trying to track down US equivalents?
D