Don't know a lot about this procedure, which is usually done to alleviate problems w/ urination due to enlarged prostate, but here's what I found about it (an excerpt describing possible issues after the procedure):
You might notice:
Blood in your urine. This shouldn't last for more than a few days.
Irritating urinary symptoms. You might feel an urgent or frequent need to urinate, or you might have to get up more often during the night to urinate. Most men experience burning, especially at the tip of the penis and near the end of urination. These symptoms generally last about a week.
Difficulty holding urine. Incontinence can occur because your bladder is used to having to push urine through a urethra narrowed by enlarged prostate tissue. For most men, this issue improves with time.
Urinary tract infection. Urinary tract infections are a possible complication after any enlarged prostate procedure. The risk of infection increases the longer you have a catheter in place.
So this article said the burning may last about a week - in your case, you're at 3 weeks. So it sounds like this is a somewhat common symptom, but in your case it's lasting longer than expected. I would speak to your Urologist/Surgeon about this & see what they suggest. They may be able to prescribe smthg that eases the discomfort, or if they think this is outside what's considered 'normal', may want you to come in for an exam and/or some tests...
Good luck - hope you don't have to suffer with this too much longer...