plaited extensions

i honestly dont know anything about extensions...but the back of the neck around the hairline, is very sensitive. this is why for example, when someone gets a short haircut, and clippers are used at the nape, they dust it with powder to keep some of the itchiness down. it might just be that your skin got irritated from all the stress on your hair, or from whatever was used to apply the extensions. i wouldnt wash it, just for the fact that you might make it react even more. what i would do, is get some non irritating powder or lotion to try and keep the itching down until it goes away, and if it doesnt go away, i would go see a dermatologist, and if they say that the rash is caused by the extensions, i would ask for a refund, or see if the extensions can be replaced with another type of extensions. like i said, i dont know much about this subject, but hope i helped a little.