I have complete empathy with you on this.
I was diagnosed with PD nearly five years ago and I can point to three step changes, relatively quickly. I chugged along with initial symptoms for about two years with a gradual increase in level of medication (Madopar). The first sudden change was a sudden increase in akynesia (freezing). The second - suddenly starting to get switch- offs, going from reasonably OK to a zombie like state within minutes, these lasting between half an hour and two hours. Sometimes I just work them off, sometimes I just give into them for a while. The third step was a sudden increase in Distonia, particularly the facial muscles that can be quite severe.
I have tried every agonist there is except one but cobeneldopa (Madopar) is the only drug I can get on with.
I can also relate to tiredness, but I'm approaching 78 so have to expect this.
It's strange but my Sister has the disease and her symptoms have simply got worse over that period, without any step changes. She's still chugging along. Mohammed Ali has been diagnosed for, I think, over 25 years. His symptoms have, from what I read been very gradual.
I have to mention stress, anxiety and anger, I find any of these bash my symptoms hard. Recently I was involved a dispute with a company that fleeced me. It affected my symptoms greatly for a few days.
Keep busy and good luck, you sound the kind of person who has a strong will.
Sea angler, Please note the new photo. My magic mirror now says I'm now fairer in face than you.