Sounds like a bad reaction. It's moved down your arm which makes sense since you pinned your delt its moving with your blood flow. It's happened to me on a strong test/tren/mast blend in my quad. I was literally crippled for like 4 days could barely walk, leg was all swollen but not at the injection site itself. To make it bearable I did 1mL of blend and 2mL's of sterile oil. That cut it enough.
Definitely tell your source they'd want to know and you might not be the only one - in which case they got bad powder.