Why are my contact lenses blurry/uneven?

I have worn contacts for 12 years and in the past 2 years, have had problems from time to time with blurry vision in one eye. I saw an ophthalmologist a few years ago, no problems then. No pain, no dryness, no redness. Yet my previous brand (coopervision - encore 100's) had so many problems that I ventured to try some new brands. I now have proclear monthlys and am having similar problems. The annoying thing is that the "one eye" blurryiness is not always the same eye. 2 months ago I could barely read out of my right eye, now its my left. What is going on?! Should I be seeing the ophthalmologist again? Am I just sensitive to "new" lenses since I just started the new set today? I've tried 5 different brands and had problems with all of them… I just want to be able to see again! I can't wear glasses due to migraines, they hurt my head and neck to the point of missing work. That is also consistent across three pairs of glasses over the last 5 years. My RX is -5.5 left and -7 right.
Added (1). One more detail - I am 26

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