Normal for residue to be left after a relaxer?

I used a relaxer two days ago. I used the neutralizing shampoo until the lather was white. My scalp feels dry , itchy and it might just be my mind because I'm paranoid but it feels like it might be burning a little. It seems as though there is some relaxer residue left in my hair. Is that normal? I'm terrified I spent all day yesterday crying because I'm scared off what might happen. I washed my hair with the neutralizing shampoo like 5 times and it's almost gone. What should I do? Please help. I'm never relaxing my hair again...