Sounds more like a wearing on problem. Have you changed the type of sinemet you take recently, or the dose? Is it generic or branded? Did you increase the dose as your doctor suggested, and if so what happened......

Wearing off and wearing on can give exaggerated 'symptoms"......

Sorry, just read that is a generic, so is it the same one you are used to taking?
And did you get a prescription refill immediately prior to this effect?

There is quite a lot of latitude in active ingredients allowed for generics, my guess if this is happening at the beginning of your dose and not before meds, that you are getting too much...... or maybe you are developing a sensitivity to it......

Wish I could help more, it is hard when even your doctor isn't really able to tell what is going on.......

Oh, another thing that I noticed is that you say you still can't walk many times............

So, does this happen every dose, or does it improve through the day?