FD,
I have had a similiar problem, in fact a few years back I suffered a barotrauma (no. 3) on descent which prompted some surgery to clear my sinuses.
I am now very conscious of equalising and I dont go anywhere without a decongestant (drixine) in my flight bag. Last week I could feel crackling on climb in my nostrils. After a couple of sprays I coughed up a rather horrible "mouth oyster" which cleared it up nicely.
I think I may have a slight allergy as this happens only rarely. If you fly and are prone to ear blockages, I suggest you always carry a degongestant for which is safe for use while flying.
Cheers