It is very strange that I can't use a towel after shower. If I were to do that it opens the door to a skin reaction that is similar to those caused by an insect bites! What might the cause of this?!
Have you used the same towel that caused you to have that rash for the first time? Have you tried using a different towel? It is hard to just say what kind of allergy it is without taking thorough history of your allergy. I think it has something to do with that towel.
Are you washing your towels in something different than what you wash your clothes in? It could be the detergent you're using. Has this always happened?
If it's not the laundry detergent, it maybe the quality of the towel. There are some people who are allergic to cheap materials or the pesticides used while the cotton was growing. It can also be the dye used.