Opioid has stolen my urine

[Reeljh]

I I take Oxycontin ER and oxycodone I have been on the same dosage for about a year all of a sudden the other day I could not pee had to have a catheter wore it for about 3 weeks went back to the urologist and everything is fine needless to say a week later I have a catheter again please help what is going on I know this is a common problem but I'm not taking anything new my routine has not changed any experience or advice would be greatly appreciated