What Causes Itchy Skin Colored Bumps On The Face And Arms?

i have very delicate skin on my face which used to be very smooth all the time but has started coming up in skin coloured bumps they do not itch but do make my skin feel more sore and sensitive and look very unsightly. it comes and goes lasting for a few days each time, doesnt seem to coincide with monthly patterns. Also in the last 6 months i keep getting a rash on my arms and legs which starts with skin coloured bumps which sometimes itchy and sometimes dont, theyare like patches of chicken skin, Sometimes they turn red and smooth and really itch and last for several weeks at a time. It could be keratosis pilaris but i read that that is usually not itchy. It is really starting to bother me now as i spend more time with the rash then without. I was recently prescribed prednisolone which made my skin perfect but as soon as i finished the course the rash on body and face bumps are returning.