When it's acute like that, no, I'm not sure exercise is the best option. Rest it, with some motion. When it's not screaming--can you find a Neuro Muscular Therapist? I've had great back-pain help from them. Different from "normal" massage; in some places, they'll claim "deep tissue" but that's not quite as good as the real NMT.

When I do back hyperextentions regularly, along with a baby-routine of situps, squats, and pull- and pushups, I don't have pain. When I am pain-free regularly, I "forget" to train, and then I'll do something that hurts.

A yoga routine built from the Ali McGraw tape also helps keep me conscious of what's happening.

AAA has prevented a lot of backaches, too, but that won't help you today.

Topicals--for me, I would try ice today, and aspercreme, and save the heat for a bit later.