What causes trouble urinating with back pain?

See your doctor or go to the ER ASAP! These are signs of either a urinary tract/kidney infection or even kidney stones... I have problems with kidney stones and infections and these are the same symptoms that I get. You should also go if you notice blood in your urine... it will usually happen at the end of the urine flow. and if you are a guy you need to be checked for prostate problems because these are also signs of prostate problems , including cancer... Just get checked out right away... and I hope you feel better soon... good luck!

There are several things that could be the root cause of difficulty urinating. Could be an enlarged prostate. See your doc as this is a major issue in some men and a few are cancerous. Two, you stated you have back pain. Your trouble may be with a nerve coming out of the lower spine that is related to bowel and urinary issues. Third, as Kaismama said, UTI's are a common culprit.
Anyway, for all the reasons listed above, you need to see a doc.
Good luck and good health,
Sweet Hippie

This could be a symptom of a few very serious things, please see a Dr asap. Hope this helps.

No doubt about that, a urinary tract infection. I would see a doc asap you need an antibiotic. Drink alot of water, it helps make it easier to pee.