if you want to start eating healthier the simplest way is to track what you are eating and shoot for a 30-30-40 balance of protein:fat:carbs.

stay under a daily limit of about 3000mg of sodium and 80g of sugar. both of these are higher than the ideal but it is virtually impossible for someone eating a 'typical' north american diet to immediately drop to ideal levels of sugar and sodium intake. these 'limits' are just to ensure you arent chugging crap like corn chips and mountain dew all day.

if you sign up on MyFitnessPal you can customize your goals to those ratios. i highly recommend it. if you have a smartphone then adding to your nutrition diary is even simpler since you can scan nearly everything in.

make sure youre getting enough vitamins as well, especially vitamin D. if youre just sitting in a dark room all day then you need at least 2000iu of D.  or get outside: the body can produce up to ten times that amount from just half an hour of direct sun exposure.

i dont mean to trivialize your headaches but most peoples ailments are a direct result of their diet, water consumption and (lack of) activity level. get these things sorted and THEN start to diagnose whats wrong with you - if anything.