I was going to suggest that for a person with allergies, I would leave it to professionals. But I am still under the influence of the customer service related thread going on elswhere on APUG and realized that trying to get answers from people who are supposed to know them might make an allergic reaction and a trip to the emergency room seem more pleasing.
All I know about wasps is that if there are two or three always present then it is an issue of nearby or concealed nesting - I would bet you just haven't found the tricky little place and the tricky little way they use to access it, and your darkroom. Its amazing how little room they need for either. If not professional help, someone who is likely to suffer less dire consequences from a potential sting should go in there and perfom a more thorough inspection that you would under the duress of fearing a potentially very harmful sting.