PIP below injection site

I injected 0.6ml test e 300 into my right delt, 3 fingers down as normal. Day 1 and 2 after my delt felt fine but now I have a really bad pain like 2inches below the injection site. It’s as if it’s travelled down my arm. Area isn’t red or swollen, just feels really tender and hard, just wondered if it’s something to be worried about or will clear up with time? I’m on day 7 now. I have amoxicillin at hand if needed.

Cheers