Hello Zoe and welcome.
A mild discharge (blood stained) can be considered normal along with/during a UTI. But you have been treated for the same two weeks ago, so this can be ruled out.
But if you still have some pain in your lower abdomen, the swab conducted was the right choice. I would also advise a transvaginal ultrasound
just to make sure all is well.
Please do not worry or get anxious, I an sure a will be fine soon, and even if some abmormality is found, youe doctors will surely help guide you to perfectly gokd health.
Hope this helps.