I gave myself my bi-weekly testosterone injection 6 days ago. On the 3rd day after the injection my thigh muscle swelled up and is extremely sore. It is not getting any better after 6 days. Any reason to be alarmed?

Might be something unrelated to your injections. I would go to your doctor and if you can't get in today, to the Urgent care/ER.

You could have injected yourself improperly. A doctors visit is in order.