Brief Answer:
Please get a urinalysis done, and an exam.

Detailed Answer:
Hello and welcome,

Painless bleeding into the urine should be looked into, so I advise you go in to have an evaluation started. First order of business should be a urinalysis. This can confirm that it is blood and may give indications as to the cause. The most common causes are infections, anywhere in the genitourinary tract (bladder, prostate), and urinary tract stones.

There are a variety of other causes too. Strenuous exercise can cause bleeding into the urine, and it's not entirely clear why - possibly from muscle cell break down or dehydration.

Then there are inflammatory causes, which are less common. And malignancies - although these are less common relative to the other causes, it has to be looked into.

Occasionally a man has hematuria (blood in the urine) and a cause is never found. In these cases, they are just "followed" with scheduled check ups.

So - the thing to do now is go in and get a urinalysis to start with. If there are signs of infection, a culture should be done. If not, imaging tests are done.

I hope this information helps. Please let me know if I can provide further information.

---