NorCali, Grungehead raised the important point to affirm what you're experiencing - reduced tolerance. Some call it 'reverse' tolerance.
I don't know how old you are nor your drinking history. What I can say is my own experience: I'm 57 (and a half); I've had quite a few sober periods and quite a few slips and relapses. I'm in a relapse right now - though waiting to hear from my doctor on Monday to help me with a home detox safely. And, I certainly notice that I feel incredibly ill and drunk quite quickly with smaller quantities of the same alcohol I'd used for years (white wine).
Don't mess about with this, given you've noticed this reverse tolerance. It's not a good sign. I hope you can see your doctor or any kind of medically assisted withdrawal agency to help you stop drinking safely.