Yes, I had appendicitis at 14, required an emergency appendectomy. I was sick for 2 days prior, had no appetite, while this pain just below my sternum kept growing. There was no pain where the appendix is actually located, which I later was told is typical.
At the end of the second day I suddenly became extremely weak, and sorta swooned onto a sofa and couldn't get up. My parents took me to the ER. The doctor later told me as soon as he opened me up my appendix burst right in front of him. Fortunately they were able to drain it off and no complications developed.
You may want to consult with a doctor, or consider an ER visit if this does not get better. Sometimes an appendix will improve, then worsen again, then improve, back and forth over weeks, as your body fights the infection.