Hi .. I Have A Very Sore Big Toe On

Hi .. I have a very sore big toe on my left foot ...the nail at the top is slightly coloured yellow and it is thickened ... it seems to be sore when I put pressure to the nail or even if I turn over in bed and it hits the mattress, it dosent appear to be ingrown could it be a fungus infection .? Will it go by itself or do I need to get it looked at ?