Try putting a pad over your clitoris and using a vibrator externally, until orgasm. That should clear out the congestion that happens when stimulated. If something remains after orgasm, you might have a cyst or something like that. If so, see your gyn.
It sounds like you get the blood congestion in the area and then it does not have the spasms to move it out again. Why don't you just use a vibrator?