Try antiperspirants, they're different from deodorants!

Apply baking powder to your sweaty armpits. Just mix it with honey. and apply.

My mascot, Poe smells like a winner! Go Ravens!

Try adding sodium bicarbonate baking soda to your bath and applying baking soda powder under your arms. Also, air out the suit!

Come to canada we are freezing our asses off could use the extra layers

Nose clips!

I feel for you OP, this heat is maddening. Ask your employer to dry clean your suit, invest in some clinical deodorant, and perhaps consider making some small changes in your diet. It'll be autumn before we know it :)

Stick some air freshener's inside there

You need prescription grade antiperspirant! I use it once a week, blocks the sweating through that area, so no odor! I doubted it until I tried it!

That's pretty nasty.. Maybe try switching to a Stronger brand and apply just before and after you get into your costume?