In addition to reiterating what has already been said (Though the input is correct; your coach will likely be able to give the best input.) I'm going to try to actually answer the question.
When you say "very amateur" I think you don't actually understand what the word "amateur" means, and may not be in a coaching situation. If that's the case, then you really should be much more careful in training situations, as injuries could always be more serious.
It isn't entirely clear to me what you did. There are a number of possibilities, and your description is pretty vague. If you were just applying pressure straight to the throat in something like a paper cutter choke and your partner was trying to fight that with a bridge, then the risk of neck injuries is pretty high. If your opponent was trying to bridge and wound up in a wrapped choke, like a north/south choke or a guillotine, then that'd be weird (though I suppose not impossible) and would likely still increase the risk of neck injuries.
There's a reason that a grappling coach (who's any good) will not just teach you to unilaterally bridge on your head while in side control. The reason is that an bridge does put a lot of strain on the neck and can cause injury if additional pressure is added. Moreover, bridges can be countered in ways that are not exactly desirable for the bottom guy.
My advice is always to seek the advice of a grappling coach who can work with you on this stuff. Someone who can see the weird stuff you're doing is going to be way more helpful than I can be over the internet. That said, I recommend that you and your friend attempt to learn a lot more about attempting side control escapes, since that sounds like it was likely the source of this particular injury.
lol ok we had a big misunderstanding about what went on. when you said it was vague i was like what?! Now i see. I didn't touch his throat, it was the beck of his neck that i was pushing against. and his for head was against the outside of my right knee (he was at my side, i was on my back). i wrapped my right arm around the back of his neck (like friends do to one another) then i put my wrist into my left arm like you would with a choke and basically pulled his neck toward me.