I have real bad back pains in my lower back and so sometimes I make take a couple of pills to help me sleep or with the pain. But every time I do I always scratch my arms and legs its like I have hives or something.

You are allergic to one or more of the medications in the pills you are taking.  Obviously, stop taking those medications, and seek medical advice as to their replacements.  Do not make the mistake of continuing to take the medication, as the allergic reactions MAY get more severe, possibly to anaphylaxis, and potentially, death from asphyxiation.

because you have a slight allergy. it's not uncommon... see if they can prescribe you something else or take benadryl when you have to take the pain meds