dermadoc has good questions
If it's showing signs like, alot of redness, if you have a fever, are any others problems follow. For most people, there bnodies form abcesses, swelling and hardening of tissue around injection site. Because it's a foreign agent entering the body, and this is just a natural reaction. Goes away in about a week, and usually returns with every injection. The other signs are what matter, and also, your doc should be able to prescribe the antibiotics without the blood work if she feels you need it. W/O blood work, they usually prescribe broad spectrum's, this is bad b/c it kill's your natural flora and lower's your immunities. Doc's don't usually like that, but they can do it.
Good Luck