Thank you for asking HCM
I have gone through your query.Your problem is most likely inflammatory bowel syndrome
.A consultation with gastroenterologist will be needed to rule out that and what type it is.A colonoscopy might be needed.I usually treat such condition effectively with aminosalicylate drug like mesalazine. For some i advise corticosteroids
and immuno suppressive therapy.Your head ache and flashes of light could be neurological symptoms due to vitamin B12 deficiency
.I usually give vitamin B12 injection
initially followed by supplements.With proper therapy you will get remission.Hope this may help you.
Let me know if you have any further query.