Bruised thighs?

So I had sex for only the second time yesterday, and it was painful again, which makes sense because he's very large and I'm very small. After we got going it felt good but my inner thighs started to really hurt? And now, the day after, they're really bruised and tender, I can barely walk. My actual vagina feels fine, just a little sore, but my thighs are super painful. Is it because we did it missionary? Like, is it just the force of him against my inner thighs that have made them bruise? And is there a way to prevent this in the future, while still doing missionary?