Help! I did this Injection into my Bicep and now I got a Huge Blue over my bicep

I got this huge blue bruise over my bicep. I injected fine then when i pulled the needle out, a little lump formed like a bruise and then 2-3 days later theres a big blue bruise spot over my bicep.

My other bicep when i did the injection of Test Ethanate, there was no problem, except only a tiny small blue spot where the injection was done. But the other bicep it was a sizable circle blue bruise.

Is that a vein popped inside or what?!

Now after few days, the pain is gone and i dont feel anymore pain when i touch it or rub it, i think its healing and the blue bruise will dissapear.

Anyone can help?