How can someone tell of they have sepsis from a recent indection?

If you are alive: ...And not in an icu, you probably don't have sepsis. Actually sepsis is just broadly defined as high or low temperature, high or low white cell count, and fast heart rate with fast breathing. Usually this is caused by infection, but not always. If you are typing on a keyboard, you probably don't have severe sepsis or "shock".

Basic signs: Heart rate > 90 breath rate > 20 fever > 101 increased white blood cell count see doc if concerned about sepsis asap.

Clinical diagnosis: Sepsis, particularly unrecognized sepsis is potentially life threatening. If you think you have sepsis, you should seek medical attention immediately. Look at the SOFA score to see how clinical information is put together to determine if someone has sepsis https://en.wikipedia.org/wiki/SOFA_score