PD is a strange disease as you probably know, it affects everyone differently. The drugs that are available affect people differently also. One person may have great success with a drug while someone else has no benefit at all.

Generally speaking sinemet helps with tremor, rigidity and stiffness. Over time the effectiveness diminishes and increased dosage is required which cause a whole new set of symptoms.

Do you have a regular neurologist or a MDS (movement disorder specialist). If you don't have a MDS I suggest finding one.

Hope this helps, good luck.