Hi Mc, welcome to the forum. It sure sounds like you have some sort of allergy. Of course I'm no doc, just a grandma with allergies.
You might try keeping a daily journal. I personally like the daily calendar type, but any old notebook will do. If the pages aren't too large, keep one page for each day, every day, not just weekends.
In the journal, write down the time and everything you eat or drink, medicines too. Write down contact with the cats, things like cleaning the litter box. Then write down any symptoms. Since you wake up Saturday with problems, pay special attention to Friday's foods and activities. If you go to a bar to unwind, it could be allergy to smoke or food or something you drink there. If you go to a movie, play with the cats more ...
Since you seem to have some ideas on what makes it better, write that down too.
Of course, it's a good idea to see an allergist and get some testing done. That's where I started. I get injections weekly and have no more pollen or dust allergy symptoms now. The food journal was the idea of my allergist, and it helped me find my food intolerances. No longer miserable!
At least the project is free.