Could you maybe upload the sounds for us to hear?
I would suggest like others have said...turn the gain down on the amp a fairly significant amount, so everything still sounds heavy when you play it but the excess fizz from too much gain isn't in there.
How are you setting up your mic? If it's directly infront of the cone/center of the speaker, try moving it to the side a little more, or angling it to make it off axis and actually be flush with the paper of the speaker instead of the cone.
Make sure your amp is really loud too if it isn't already, as the more poweramp saturation you get, the less fizz you'll be getting from your pre-amp.
In terms of the mixing process, it's generally best to try to have a killer sound before you dress it up with EQ and compression and so on, but I generally take out some of the high end, anywhere from where the EQ starts down to even around 10k, and I find this gets rid of a lot of the high end fizz and makes the guitars sounds much better, but be careful. It all depends on the type of tone you have, as this could be way too much removal with your particular sound, but it's always something you can experiment with.
Alternatively, you could use a multiband compressor to single out the frequencies you want to get rid of and cut them out, and then experiment with boosting some of the better frequencies like te lower mids to give it a nice growl and make it sounds tighter and cut through the mix better.
Keep in mind, a good drum mix will make guitars sound tighter than they actually are, so experiment with the kick drum a lot in the mix and try to make it compliment the guitar sound well.
Hope this helps...
