Well for starters, can you maybe switch to a different ROA? or pouussibly pick up something else to take? like can you grab some suboxones? (not sure what you have been taking so disregard the suboxone if you are using something other then opiates).
Well, a quick-fix, would be the makeup route.
How to use make-up to hide scars & bruising
You can pick up most of this shit at your local CVS or Walgreen's or even cheaper at Walmart. The entire set will run you about $50 and that is if you are buying the cheap shit.
I'd only worry about that when the time comes where you have no other options but to go that route.
As for what you can do now, I suggest getting like some Neosporin Scar ointment. Then look around for some Scar treatment. or something that women use for stretch marks for when they have kids.
You can mix a 50/50 ratio of the Neosporin and the Scar ointment (anything that shows it removes scars). Apply on both arms after washing clean with soap and water. Gently rub into the effected areas with clean washed hands. Re-apply as soon as you sense that the previous treatment had rubbed off or something.
I don't recommended IV with either or skin treatment/makeup.