The usual medication on the case of enlarged prostate is often herbal, I ever read various points about saw palmetto and used to get prescribed tadenan (African plum tree extract, sadly not available anymore).
Thai herbal medicine has options for this usual men trouble.
I can not remember the name but the herbal shops near Tha Chang (Sanam Luang) have large bags of 200 pills for 200b if i remember well.
If you can not speak thai just get a translation of "prostate big" on your phone and they will give you some. (every provincial cities might have an herbal shop).
I am NOT a doctor but it worked very well on me and could at least make you feel a bit more comfortable. feel free to show those pills to your doctor.