Before you jump into trying to eliminate a tumor which may not even be present, I suggest trying to make sure there is one. Perhaps a second opinion and/or perhaps a Navarro urine test for cancer. See:
http://navarromedicalclinic.com/
In the meanwhile, you might go ahead and get some good Essiac Tea - as it is a great overall cleanser and has historically had some good results against cancer (though I would not rely on it as a sole item for cancer if I knew I actually had cancer). Also, eat plenty of watermelons. They are great for the kidneys. So is watermelon seed tea.
You might find some helpful information regarding frequency here:
Natural Help for Overactive Bladder
I agree that a second opinion is the best first step.
Good question about the iodide recommendation. Normally, iodide would be a good idea with low TSH levels. Perhaps you should ask the doctor for a more detailed explanation. Otherwise, you may find help with the question at the Iodine Supplementation forum.
Not saying that this may be the case with your doc, but some docs are fairly clueless when it comes to iodide/iodine.
Blood in your urine and the urge to urinate frequently can also be caused by uric acid crystals in your bladder. These are formed when you don't completely empty your bladder and some urine stays in your bladder where it forms a pool and the crystals form there. When this happens, it is often associated with a high protein diet and not taking in enough fluids. I know, it once happened to me. This generally happens when a man's prostate becomes enlarged which restricts the urine flow. Don't know if a restriction can also happen to the female anatomy or not.
When a doctor keeps information from me or doesn't explain something to me I fire them - never to return. Get another doctor and have that one look at your earlier exam. Also if your doctor is in a clinic go to another clinic.
If you have urethra blockage, it's a simple though painful (in the healing process) procedure to correct it.