When you colored your hair it may have dried your scalp out too much?
Once I went through a period of itchy scalp and it was so embarrasing I thought I had lice or something.
I went to the Doc's and he said it was nerves, he was right. As soon as the problem went away in my head so did the itchies.
But a good oil treatment may help you if it is just dried out. Olive oil is great if you have it or any oil. You could also try Dandruff shampoo now, it is much improved with conditioners and doesn't smell awful anymore. I use it sometimes just for a change in shampoo's but they say it is good for itchy scalps. Good luck!