Ive had shingles a year ago.?

which left me no problems, 2 weeks ago i had viral conjuntivitis, was given antibiotics, and penicillen . now ive got a terrible itch down my backl and between my shoulders its constant and there all day tired antihistimenes and steriod creams but no avail.. there is no spots or marks on skin.. its driving me mad , anyone got any ideas wot it could be ....thanks