Is It Safe To Take Allegra And Zyrtec For Rashes On Body?

Rusty wire picture few months ago in hand. Healed but lump size of nichol appeared couple of months ago and have rash over 50% of my body doctor says is allergy related, taking Allegra and Zyrtec for two weeks no real change. Not sure if puncture has anything to do with it but seems I ve read of something other than Tetanus you can get from rusty nail?