I am on sinemet and comtan which is similar to taking stalevo.
I have had more tremor since starting comtan, I have virtually none without it, but it is so good with mostly everything else that I accept that as a lesser evii.

I get neck pains as a wearing off problem. They are similar to what you describe, and I did not have them before. Wearing off and wearing on have given more problems than before.

I would agree that on entacapone it is harder to tell what is on and what is off, because the wearing off and on is a bit more acute and it's harder to tell which is which. I have found out by trial and error, and missed doses what to expect, and that I can wear off hard and fast, and thats when things are more painful.

I try to anticipate when the best time is to take my next dose, and not to wait until I have actually worn off. This varies according to whether I have spent hours at my computer, or been out and about. My best predictor that i am about to wear off is that I notice I am feeling 'normal' or asymptomatic, and am at my most functional! This is usually followed very shortly by wearing off symptoms. If I remember this is when I take my meds, right after I notice, but I don't always catch the moment. (Somebody once wrote about this being the best time, and it works for me - whoever you are, thankyou!) When I get it right the transition is smooth....

The first part of your description sounds as though you could have been slightly undermedicated and needed to bring your doses closer together rather than increase them. You have changed things since then without it helping. I'd go back to what it was when it was helping, and make any changes very slowly, so you have time to see what is really happening.
say, just increase the morning dose when the tremors were not being improved, and watch and see, the little extra could help later on too. If this doesn't help then bring the second dose half an hour closer..... and so on. With your neuros help, of course......

If you make it a gradual process you can see what is happening...........

It's one of the worst things about Pd, trying to get the meds to work for you.....

Lindy