Condom came off during sex. stopped. very painful urination afterwards eased of completely the next day. hard to get erection 3 days later. okay?

Spermicide?: No STD can start to cause painful urination or any other symptoms sooner than 2-3 days after exposure. Perhaps the condom contained a spermicide, and some spermicides (e.g. nonoxynol-9) can irritate the urethra, with painful urination that clears up within a day. No infection or inflammation intereferes with erection, maybe anxiety or worry about the event. But see a doctor if symptoms continue.