Swollen butt!

[TigerMom]

With the intense type of downhill MTB that you do, it sounds like there is a good chance that you really did fracture your sitbone.

3-6 foot drops! I'm still impressed.
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2012 Specialized Amira Elite, upgraded carbon handle bars, Jett saddle 143mm switched to 145mm 2012 Selle Italia Max SLR Gel Flow saddle

2011 Specialized Ariel Sport,suspension post,Serfas Rx Women's Microfiber saddle

[Sky King]

also could be a pulled muscle or irritated fascia perhaps. Will be interesting to hear what the doctor says. but with all that up and down and using tension in your muscles you could have smacked the area hard on your saddle or have a muscle tear.