Hi. Thanks for your question. I am a board certified neurologist in the U.S. I will be happy to help.
How old are you?
Also, are these head and neck movements tremors, or something different, like a writhing irregular movement?
OK. Thank you for your reply. One option you can discuss with your neurologist would be to consider adding a medication called Amantadine, if you have not tried this. Amantadine can help with dyskinesias and also with more typical Parkinson's symptoms as well. Another option might be to switch to a long acting form of Parkinson's medication and perhaps lower the dose of the Madopar, to see if that might lessen the dyskinesias, while helping your other Parkinson's symptoms at the same time. In the US, such options include pramipexole and ropinirole in the extended release forms. Another option that you may consider discussing would be deep brain stimulation, which is a surgical option that can be very helpful for many patients with Parkinson's Disease.
Hopefully this has been helpful to you. Please let me know if you have more questions and I will reply as soon as I have time to do so. If this was helpful, please remember to rate me highly. Bonuses always appreciated. Best of luck.