cracked rib or disc?

[mum]

I took a little tumble off a horse yesterday, and it appears I no longer bounce! I landed on my back hard enough to knock the wind out of me but it was into a few inches of sand. Anyway, I was in terrible pain last night, the worst being when I try to lift anything, like just my tea kettle. It is a bit better today, but I still cannot lift anything. When I am still, it doesn't hurt at all, but certain movement set off an awful spasm type thing Is that a symptom of a cracked rib or disc or vertabrae? If so, is there anything a doctor can do? I already intend to rest rest rest.

Thanks,

mum