Do I have a UTI? Home remedies?

Mae

After more than one round of sex, it usually takes a while for my labia to recover, but more recently my urethra (sp?) is irritated, it hurts when I pee, and I feel the need to pee more often than normal.

Do I need to get antibiotics or can I just treat it at home? I do pee after sex, but do I need to wash myself before another round?