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Just check and see if there is frictional injury at the head of penis due to sex. If yes, then keeping the area clean and applying an antibiotic cream may help.
If there is no injury, you could either have caught urinary tract infection or bacterial vaginosis. Testing for them can be done through urine samples and swabs from head of penis, respectively. Since it’s a monogamous relationship, chances of STD are less, but if all the above causes are ruled out, then STD panel will need to be done. Treatment will depend on the cause. Take care!
As suggested, you appear to have a urinary tract infection, which you did not necessarily get from your wife. See a physician and in the meantime drink cranberry juice, which is a mild bactricidal.
Sounds like a urinary tract infection. Call your doc and get on some antibiotics.