The reason your uro's office told you not to use trimix any more is because your nine hour erection scared him. If you do decide to continue your efforts with trimix you will need to use a much smaller dose, but more important, you should be way quicker dealing with an erection that lasts too long. If you were injected at 1:00 pm you should have started with the Sudafed at 4:00 (maybe 4:30) pm and you should have been in the emergency room by 6:00 pm at the latest. And erection that lasts more than 4 hours is a medical emergency.
You are, apparently, one of the guys who have really strong veno-occlusion. As such you will need to use tiny little doses of trimix. The good news is that once you find the right dose your cost per use will be really low. The bad news is that you'll have to be really careful with your dosage to stay out of the Emergency Room.
You asked whether you should switch urologists. You may have to. You've traumatized your current one. You may be able to reassure him that you will take more care moving forward.
Here's a link to some advice about
over-long erections from Memorial Sloan Kettering Cancer Center.
/www.mskcc.org/cancer-care/patient-education/priapismNote that they say you should take the Sudafed after
two hours and that you should take the Sudafed four at a time (4x30mg=120mg) and they should be regular Sudafed, not the long-lasting extended-release varieties which are released too slowly to do the job.