Your lucky it was sand.
I have had quite a few run ins with the wipe out.
I remember one time, I was screwing around in the shore pound during low tide at the end of a swell, and a nice set came in, of course being that I was only about 30 feet from shore, I didn't stand a chance of paddling out to catch it in time, so I waiting for it, and figured I would catch the white water, but it never broke out there, and the dang thing just kept rolling in, and it broke right under me and I was paddling for it, just dumb luck I was right were it was breaking. Tides were playing tricks on me that day, it was in northern florida.
Anyway, right as this thing picked me up and I thought I caught it, but it caught me. It picked me up, like 8 feet in the air, and slammed me down, right into water that was only a foot deep. SHORE POUND. I smashed down on my left arm, and thought I broke some ribs, I limped walked away from that one hunched over, thought I broke my arm too at first.
And of course, I have been slammed into rocks, reef, pebbles, had my leash wrapped around my neck, etc. etc. thought I saw a shark right next to me, been slammed into by ice chunks.
The only advice I can give you is Shxx happens, and at least you will have something to tell your grandkids.
Try downhill skateboarding sometime, once you scrape all the skin and soft tissue off the palms of your hands and knees, and have to use those hands to pick pebbles out that are embedded in your head out, so the blood gysers can gush, the sand bumps don't seem so bad.