What Causes Soreness Of Anus In Kids?

hi my eight year old son has very sore anus. There are no signs of thread worms and no redness. I'm using sudocrem and he still complaining of it being sore and itchy. Should I make an appointment with GP as this has been on going for weeks now? Would like some help as he has just woken up from sleep and only went to bed at 8.30. looking forward to reply. Many thanx