I have a scaly looking type of rash from my labia majora to my butt cheeks. Nothing inside the vagina, although I get an itch right by the opening which is intense at times. And lately its been intense and painful if I scratch directly on the rash. I've been using a yeast infection cream to relieve pain but it's still there and worst. It's been about a week. It all happened after I used a razor that I left in the shower and then reused. What can I do to relieve the itching? Or to lower the inflammation by the scaly areas?

You will need to see a doctor to have this properly diagnosed and treated.

Meanwhile, try some cortisone spray (or cream, but spray will be easier there, despite being costlier) after washing with unscented soap, rinsing well, and airing out by staying naked as long as you can.
I have extremely dry northern European skin which is prone to every condition in the book, and I use cortisone cream a lot. I just had a bout of scaly itchy skin in the inside bend of one elbow. It started from a mosquito bite.
I'd stop shaving.