What should I do in this situation?

I used to never get itchy underarms when I would shave and now I do. Every time I shave, shortly after, my underarms start itching bad. I have used older razors, BRAND NEW razors, Bikini zone. Nothing works. I go to work and try so hard not to scratch till I can't take it anymore and start scratching like an ape. One time I was getting something for a customer and my under arms were itching really bad and the more I ran around the store trying to hurry and get stuff for her the worse the itching became and I was trying not to scratch but couldn't help it anymore, I just had to and I know the security could see me on the camera itching my armpits and running around like a wild monkey. Please help. I am so embarrassed.