I wanted to start this fan fiction off, with Sonic being a chronic headache and migraine sufferer! as I have suffered from regular headaches for the past 20 years myself. So I felt Sonic needed to experience them too!
Sonic has suffered from chronic migraines and headaches since he was a child. He always has Ibuprofen and Sumatriptan stored in his glove cuffs to manage the pain in case an attack happens whilst he's out on his adventures. He's always been embarrassed about it, as headaches and migraines are wider known as something females suffer from more than guys. Amy Rose suffers from migraines too, but Sonic's NEVER told her about his migraines. He doesn't want a fuss.
Sonic's migraine auras have been so bad over the years he's ended up being hit by Eggman's robots on numerous occasions, as he either loses his vision for some time, or it becomes severely distorted from a migraine aura and he doesn't see an attack coming.
Sometimes, Sonic's migraines hinder him bedridden for a day or two, and he stays in his room, and lays in pitch black darkness. Or he'll wear dark sunglasses until it passes over.
Eating too much chocolate, not getting enough sleep, or being exposed to flashing lights trigger a bad headache or migraine, so he actively tries his best to moderate his chocolate intake, get plenty of sleep and closes his eyes when he sees flashing lights, or else he will be in trouble some hours later!
The hedgehog should really see a specialist to find out exactly why he has such bad headaches and migraines at his age, but Sonic being Sonic likes to brush off his condition, he doesn't want to burden the health service with something he feels they will see as a minor issue, even though to Sonic, it leaves a huge impact on his life due to their frequency, especially the older he gets.