There are all kinds of different molds that can be found in your cannabis, some of them are white and fluffy, some are darker and "patchier" in nature, and some are harder to detect with the eye. Sometimes you can smell it, it may have an ammonia smell if there were seeds that have been compressed, cracked, and the "milk" from the seed soured and molded... Mold is possible on high quality cannabis too.
Like a previous poster replied, it's a heavy pollen year too, the cannabis may be irritating your already irritated sinuses and being the final straw.