I Have Had Big Swollen Spots On My Arms That

I have had big swollen spots on my arms that itch like crazy. They go away within an hour. But what is happening when this happens from IV methamphetamine use.also the inside of my thighs in the groin area will itch extremely.. I have been experiancing athetosis for some time now. Is this maybe a reaction to iodine? Or the Ph being too far from nuetral? Or a very acidic substance? It happens at old injection sites but is not contained to these areas. Or is it that I have severe liver damage.?