This exact same thing has happened to me! I have worn contacts all day every day for 40+ years. Over the last several months, I couldn't really describe it but my eyes always felt like something was in them or on my contacts. I tried drops and different cleaning solutions. Like you, I was diligent about cleaning them and using a fresh pair every month. There were days I would yank my contacts out, once even leaving church to go take them out because they were just driving me crazy. I finally went to the doctor and she told me that everyone has tiny bumps on the inside of their eyelids, but mine were huge, caused from the years and years of wearing contacts. She gave me some Rx drops and I had to get glasses.
She said the bumps will get better but will never go away.
She said I could wear my contacts occasionally, for special occasions, but not for extended periods. I tried to wear them the other day, but by mid-afternoon I was ready to rip them out! It has been a huge adjustment for me to go from contacts to glasses, but I am trying to have a good attitude about it. Not much I can do about it anyway!
Hope you find a solution soon! I had never heard of this before, so in a way I'm glad I'm not alone. But I hate that you are going through it, too! Good luck!