You may want to get them checked by an ophthalmologist. Many drugs for allergies(and a lot of others) can cause "dry eyes" and believe it or not, dry eyes can present with very itchy, watery eyes and nothing seems to help. The problem is that your eyes may not be making the right kind of tears(due to the drugs) or the tiny pores in the lower eyeliRAB that make a thick oily substance that coat your eyes, may be plugged from all the allergy problems and rubbing(causes the pores to swell shut). Either problem can cause what you are experiencing. Your eye doc can test and give you drops to treat either problem(or both) or if neither is the problem, can give you some good prescription drops for the allergic reactions.
I have the same problem and was pouring eye drops into my eyes for years before finally seeing the eye doc and finding out I have severely dry eyes. I couldn't tell...they watered and itched like heck! But with a special dye, he could see that my corneas looked like shattered glass....a sign of severe dryness...and further testing showed that once my eyes were washed out and no allergens around, I really put out very few tears. Further examination showed that all the junk I was putting in my eyes had clogged the pores along the eyelid and I had none of the oily substance that protects the eyes, either.
So now when my eyes itch, I have drops that wet the eyes and I have an oily ointment that I put in at night and if it gets really bad, prescription drops that are anti-inflammatory that calm the eye and make more of the right kind of tears. Stopped my years of itchy eyes almost overnight. I took tons of antihistamines and got my allergy shots and did everything I could but I was treating the wrong thing.
Please see an ophthalmologist and find out what is wrong first.
Jenny