Is it normal 4 the skin around ur stoma 2 change color??

I have been having skin problems around my stoma. 1st lil itching then burning. So I'll change the pouch n it would b red n lil swollen. Use powder n seal. Now skin is grey n purpleish. Is that ok?? It Doesn't hurt or itCH at the moment.
My dr said to cut hole as close to stoma as possible n nurse said to leave an extra 1/8 th space.
Tried drs way n so far so good. No irriitation. As opposed to nurse way.