I always knew that I have dry eye problems, but recently, It's really painful and itchy. At first, My right eye was so in pain but a few day later, I began to have pain in my left eye too. I've tried optive lubricant eye drops and although it did help a little but it doesn't seem to be working. I tried to use the humidifier but nothing change. I don't have insurance so it's difficult for me to go to the doctor. another question is when I have tears in my eye, for some reason I have problems producing tears. Is that serious?
should i go to the doctor to see what is the problem?

If you can go to an optometrist they can prescribe Restasis drops to help or use punctal plugs to help increase your tear volume. Some non medical remedies can include drinking LOTS of water and flax seed oil supplements

I just had eye plug put in my right eye for dry eye. It did relieve the dryness. But the OP is correct -- drink lots of water. I still have to use eye drops with the plugs in.