"I had sex and did not urinate afterwards. Since then, my urine smells strong and I have pain in my lower abdomen."

It sounds like you may have a urinary tract infection. It is important to seek medical advice and treatment to help with your symptoms and prevent any further complications. In the meantime, you can try some home remedies like drinking plenty of water and urinating after sexual activity to help flush out bacteria. If you have any concerns or questions, it's best to consult with a healthcare professional for guidance and proper treatment.