I am a 46 year old female, was diagnosed on friday with strep, received a penicillin shot, started running fever friday evening, and still am?

Multiple issues: eg: 1. multiple forms of PCN, 2. single injection vs. continued dosing, IM, IV or oral, 3. dosage used, 4. sensitivity/resistance of the bacteria to PCN, 5. accuracy of the diagnosis of Strep. vs. other basis. 6. Commonly takes some time (a couple of days?) for antibiotic to suppress growth/kill-off enough bacteria to greatly ease of your immune system to finish job 7. Your immune system status, etc.

Not sure: when this was posted but the shot of pCN is not going to stop the fever right away. Some people have a fever that last several days after the antibiotic is started. Some people have a fever as the germ is killed and have a rash as well. This may just be a reaction to the med working. IF DOES not resolve by tomorrow see the doc again.