When it comes to allergies it is almost impossible to pin down the offending agent(s) and, therefore, treatment needs to focus on controlling the symptoms. Dry eyes is very common and can be improved by a stepwise series of therapies. First, the use of natural tears 4-6+ times/day to augment your natural tear production, then temporary punctal occlusion of the lower puncta, then temporary occlusion of all 4 puncta then surgical ( non-reversible) closure of the puncta.
Blepharitis is a condition where glands in the eyelids are not functioning normally. They become plugged and instead of putting out their normal clear, oily secretions, they put out thick, toothpaste like gunk.
The best treatment for this condition daily lid scrubs combined with warm compresses. I like to use baby shampoo for lid scrubs. In the shower, place the shampoo on your index fingers, close your eyes, raise your eyebrows (to stretch the skin on you eyelids) and scrub back and forth along your eyelashes for 3 to 5 minutes. The hot water in the shower helps to soften the plugged oils in the glands while the mechanical scrubbing with your soapy fingers removes the oils.
Baby shampoo lid scrubs will also help to wash away allergens and stimulate tear production, thereby addressing all three of your issues. Remember, this is not an instant fix. While you are waiting for the lid scrubs to have affect you can use over the counter allergy pills such as Travist, dimetapp or Zyrtec.
Should your symptoms get worse, your vision become significantly affected or things just not get better in 3 weeks or so you should have a complete eye examination by your local ophthalmologist
to look for other, less common, causes of your symptoms.