Is it some sort of autism? Or is it really just creativity/imagination that is dialed a little higher than your normal creative person? More background info: as a small child, my son had many imaginary friends and imaginary adventurers, he also did “imaginary work” at “imaginary places.” As a child he did not need me or anyone else to play with him - he could and would entertain himself for hours with the stories and characters in head. He has always had a more than rich imagination.
My ASD son is like this (although not self-aware enough to describe the "creative storm" your DS communicates).
For him, it does fall under Part B, Number 3 in the DSM-V:
B. Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at least two of the following, currently or by history (examples are illustrative, not exhaustive; see text):
1. Stereotyped or repetitive motor movements, use of objects, or speech (e.g., simple motor stereotypies, lining up toys or flipping objects, echolalia, idiosyncratic phrases).
2. Insistence on sameness, inflexible adherence to routines, or ritualized patterns or verbal nonverbal behavior (e.g., extreme distress at small changes, difficulties with transitions, rigid thinking patterns, greeting rituals, need to take same route or eat food every day).
3. Highly restricted, fixated interests that are abnormal in intensity or focus (e.g, strong attachment to or preoccupation with unusual objects, excessively circumscribed or perseverative interest).
4. Hyper- or hyporeactivity to sensory input or unusual interests in sensory aspects of the environment (e.g., apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement).
A child needs two of these, plus several more symptoms in categories A and C to have an ASD diagnosis.
I wouldn't worry too much about temporal lobe epilepsy (TLE). Even though aeh is correct, that several brilliant artists are thought to have had this (e.g. Van Gogh, Dostoevsky), you would almost certainly see seizure types that would be far more obvious in TLE.
My vote is for quirky gifted, unless there are other concerns. He wouldn't be able to control this at school if it were autism and/or a seizure disorder. It sounds like he's learning to self-regulate the intensity as he matures.
Of course, you should consult a professional if you are truly concerned! Does your DS have high levels of anxiety? Some people have "intrusive thoughts" as a feature of anxiety disorders. These are not typically pleasant, creative experiences, though.
