Anadrol
To be honest, the sensation you described in your arm could also be related to working out in general, putting on mass can put a lot of stress on your joints. As for the heart burn that's likely to be the Drol, it can be quite harsh on your stomach.
You will always experience less side effects on a lower dosage. I used Drol for 5 weeks and got very few sides (bit of acne and tightness on the chest), are you using nolva or any other anti-e?
So yes, if you can manage to split it and take half a tab that should help with the sides, but of course you will see less gains. Also, these tablets usually have a protective coating on the outside, so by splitting the tab you may be more prone to heartburn. Take with a meal preferably.
Hope this helps.