I am sensitive to clen and haven't even ramped it to 60mcg yet. 40-50 mcg is unpleasant enough for me. Infection is usually indicated by fever, chills, and intense pain. However, hardcore injection pain is very common with aas. And your taking clen which increases body temperature and does create a feverish/chilly feeling in some. It's very unlikely you have an infection, its just painful. Read this forum and T-nation's and any info you can get your hands on regarding post injection pain.