Brief Answer:
If the rest is normal, no reason for alarm, only a neuro follow-up.
Detailed Answer:
I read your question carefully and I understand your concern.
That value is indeed significantly elevated. Elevated protein in itself is not a specific finding, meaning it can be found in many different conditions, meaning infections, haemorrhage, multiple sclerosis, acute polyradiculoneuritis etc, so alone it doesn’t indicate a diagnosis, must be seen in combination with clinical picture and other parameters of the cerebrospinal fluid such as presence of blood, white blood cells, glucose levels etc.
So before you start to panic in front of all those diagnoses, if all those other parameters have turned out normal then diagnoses such as infections or haemorrhage do not fit. Tumours don’t either given the normal CT scan. Nor do conditions such as acute polyradiculoneuritis manifest with the headache, they manifest with paralysis of the limbs. Conditions like MS are very exceptional to manifest after the age of 45 as well.
So if all other values on CSF test were normal, then significance and further steps depend on current condition. If you feel well, headache is improving and there are no other symptoms then no urgent measures are necessary. Would recommend only to schedule a neurological consult to check for subtle neurological signs which might warrant tests like MRI for possibility of multiple sclerosis.
I remain at your disposal for other questions.