H.W.
Check again with the doctor about the blood if it isn't disappearing by tomorrow. Avoid sugar, caffeine, alcohol, spicy foods (all of these will make it worse). Cranberry juice concentrate (not sweetened) is fine, too.
You can get an OTC called AZO for the pain, but be aware that the AZO can mask any future labs/UAs , so I'd talk to the doc before starting to take it, esp. if they want to retest you for the bleeding.
Could you be experiencing some mid-cycle spotting? I've never heard of that much blood during a UTI. If it's coming out in clots without urination, and you are sure it's from your urethra, do check in with the doc.