Those experiencing testicular pain were the same on both the placebo and Propecia.
Testicular pain could mean many things. If it's really uncomfortable, you may want to see the doctor. If it's mild, you may want to see the doctor if it persists more than a week.
itll go mate. then itll come back for a bit, then itll go, then....you get the idea. a lot of people get it i dont think its anything to worry about unless its really painful. theres probably more posts on it.