I been goin to bathroom and been experiencing a burning itch after i urinate can i use amoxicillin 500mg to relieve it or another medication?

Vaginitis? Cystitis?: The correct medicine depends on the correct diagnosis -- and from what you've shared i'm not sure what the source of the problem is. If you have a vaginal yeast infection, Ampicillin will not affect it. If you have a bladder infection (cystitis) Ampicillin may or may not be the best antibiotic. Please see your physician for appropriate diagnosis and treatment.

See your doctor: Do not self treat, you could have a urinary tract infection or a yeast infection or other problem so see a doctor to get tested and get the proper treatment.