Hi,
Noted the history about your nearly 5 year old son having tight head and
neck spasm but no fever and in otherwise good spirits.
There could have been some activity that caused the neck muscle spasm hence the neck
stiffness and this in turn can cause tight head.
If there are no other symptoms then give him an
analgesic like
Ibuprofen according to his weight if it suits him.
Apply local Rubefacient liniment to give warmth and relaxation of muscles.
Get the neck movements in all direction and see if there is any restriction or lump in the neck, particularly of muscles.
If present then it is better to consult his Doctor for clinical examination to be sure about any possible diagnosis and have proper management if required.
Do not force for anything.
Insist with affection about any accident while playing or so,
Keep him a comfortable position in bed in a warm room.
Avoid
Torticollis at any cost wherein one gets the neck turnd to one side.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. T. Chandrakant, General Surgeon