Thanks for your query.
well......your complains are quite limited which are indicative of "writer's cramp". would like to have li'l more history about you. whether you get pain only during writing or some other work too. If your problem is confined to writing only thn we can be sure about "task specific dystonia"
Writer's cramp is a type of focal dystonia
that is specific to the task. Dystonia is an involuntary, sustained muscle contraction
. Focal dystonia affects only one body part. Writer's cramp is the most common dystonia of the repetitive movement disorders.
I do hope that you have found something helpful and I will be glad to answer any further query.