Hi
Welcome to the MedHelp forum!
What you have is probably honeymoon cystitis that happens in females after sex. Trauma to the genital and the urethral orifice, and bacterial contamination from the fingers or mouth makes cystitis prevalent among honeymooners, especially among females.
The most common bacteria that cause cystitis are called E. coli (Escherichia coli). Latex allergy from condoms, ill-fitted diaphragm, contraceptive foam or jellies, herpes and trichomona infection (sexually transmitted diseases), non-bacterial infection, like thrush, dry vagina and bacteria under the foreskin of the penis among uncircumcised men are common causes.
Drink plenty of water, cranberry juice when symptoms start and follow good personal hygiene before and after sex like bathing or washing the private parts well will help prevent it to a great extent. If this does not help, consult a gynecologist.
Hope this helps. Take care!
Bacteria gets pushed into the uretha, try to always urinate after sex to wash this out.