Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for a sudden loss of writing ability together with symptoms such as facial drooping, one-sided weakness, trouble speaking, severe confusion, or a sudden severe headache.
These can be signs of a stroke or another neurological emergency rather than developmental dysgraphia.
Seek prompt medical advice if handwriting changes after a head injury or is accompanied by a new tremor, weakness, numbness, loss of coordination, confusion, or significant hand pain.
Arrange a routine assessment if writing difficulties are persistent, clearly greater than expected, or interfering with school, work, or daily tasks.
Children may benefit from both an educational evaluation and a health review, especially when there are concerns about movement, attention, language, vision, or pain.
Every sign above is quoted from the sofidex article on Dysgraphia. If you are not sure, err upward — it is always reasonable to be checked.