I got this about 5 months in, but it affected me in the mornings just as I woke for about a couple of hours. It lasted about six weeks and has stopped now.
It was quite painful at times - a dull ache.
Yes, I've had it before in my life before taking propecia, but it wasn't the with same intensity and I worked out that it was after too much sex or masturbation.
Stick with it !