I had anal sex without protection when i took my penis out i realized i was bleeding we had both tested negative for stds before should i be concerned?

Yes!: Bleeding suggests visibly broken skin which then allows for bacterial & viruses to get into your body & cause an infection. Just because you both tested negative before doesn't mean that you're both negative at the time you had unprotected sex. It's possible to get infected a day or so before a blood test that subsequently returns negative (since down too early). That's why you need serials tests.