Could Delayed Dizziness Stem from Amitriptyline Overdose?

It sounds like your son might be experiencing an eye movement disorder, which could be a sign of a neurological issue. I recommend taking him to a pediatric neurologist as soon as possible to get a proper diagnosis and treatment. 

The blurry vision and the difficulty in focusing can be the vertigo that the ear fluid causes. It is common and it does not mean that you have a brain tumor. The ear fluid can mess up your balance and vision. Usually, it gets better on its own, but you might need medicine or special exercises if the problem keeps bothering you. 

Your phenotypes of headaches, gum pain, fear of death, panic attacks, stomach problems, and headaches after eating could be connected. You could have a condition like migraines, anxiety, or a digestive issue. Get a doctor's opinion for the right diagnosis and treatment. In the meantime, try to eat regular meals, manage stress, and get plenty of rest. 

It may be caused by the virus for instance, and your body is struggling with it, or it may be a simple dehydration issue. Drink water frequently, rest, and eat well-cooked bland foods (crackers being one of the great options indeed). If your symptoms do not improve, consult a doctor.

This can be due to various reasons. It may be because you are not taking in enough water, or perhaps you are feeling stressed or tired. Things such as not eating regularly or having low blood sugar can also make you feel this way. Drink a lot of water, take a proper diet, and avoid overexertion. Suppose in case dizziness persists, it is feasible to check with your doctor so that any serious issues will be identified.