Have Rashes All Over Body Along With Itching. Took Steroid Shot But No Use. What Is The Cause And Remedy?

A couple of weeks ago I shaved my body ( male here) like I usually do but this time I broke out with pimples all over the front of my chest, stomach, shoulders and arms. Whats worse is that it still constantly itches and my arms are now becoming really dark ( stained discoloration) with contant itching. Sun aggravates it more so I try to use Sunblock from Neutrogina. I saw a dermatoligist a week ago. She gave me a steriod shot and said that would help. So far there is no difference, rather arms seem to be getting more and more black colored. I am of East Indian descent and am dark naturally, but this goes beyond that. It also gets irritated if I were wearing any clothing that would touch the arms. I have shaved for many years with no problem. I am frustrated, itchy, and my skin looks so so bad that I am embarrased to wear short sleeves. Please help. What do I do and what may be wrong with me?