Just to clear up a few things for you, hopefully to help in support and understanding:
Anal sex -- nor any other given sexual activity -- doesn't necessarily make sexual trauma more or less traumatic. The trauma doesn't arise from a given sexual act, but from sexual violence itself, no matter how it manifests. How much trauma is experienced varies widely based on what happened and the individual: some survivors who were anally raped, for instance, experience less trauma than othrs who were fondled. So, what acts were involved are pretty irrelevant when it comes to dealing with rape, and certainly so from your perspective as a partner. It might come up in the future per sexual boundaries, but that's likely about as much as "acts" matter.
Not knowing what went on aside, it IS vital your partner gets himself to the doctor, even if he doesn't want to ask about the assault right now. from the sounds of things, he may have alcohol poisoning right now, for instance. Obviously, if he can get a full check-up and STI screening, all the better.
How you can help him is to make clear you're available to help and listen, and to let him let you know what he needs. That may be space to himself, it may be talking about this, it may be a distraction from this, etc. But your best bet is to let HIM direct what he wants or needs from you right now.
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