Photo-sensitve epilepsy?
http://en.wikipedia.org/wiki/Photosensitive_epilepsy
I had petit mal epilepsy from 6 yrs. to the late teens (one side of my body would go limp). I took phenobarbitol and dilantin 3 times a day until I decided to take my pills only every other day (then I grew out of it, but my doctor didn't want to believe me). If I went to the doctor today (35 years later), he would look at the records and tell me I still have epilepsy. Blinking lights can trigger a seizure. Right now, most likely, his body is too weak to withstand repeated visual stimuli from T.V. (maybe sunglasses when the child is monitored, but not when walking around the house, may develop more sensitivity to light).
Maybe the mother is spoiling him on purpose to make life difficult for the husband and you (using the child) in order to get back at the husband, or maybe she's just alone and doesn't want to care.
Are the grandparents trying to RUIN the child's life because the mother convinced them they should? How could they not understand the DANGERS of "SPOILING" (it actually MEANS to spoil/ruin the person) a child? Explain this to them and have your boyfriend back you up as a MOTHER.
If the boy goes to ANY school while he is still spoiled, he will get..
1) TEASED
2) get into fights
3) get kicked out of school because he acts up and starts fights
4) might eventually get into drugs
5) might learn to be a delinquent and want p 0 r n on the internet
School can be a bad place these days for a child who insists on his own comfort and pleasure because he'll pick up bad habits from bullies and "cool guy wannabees". School won't straighten out a kid who doesn't want to be straight.
EVERYBODY is trying to PLEASE him, he senses that and knows he has got you all wrapped around his finger...DON'T be accommadating and convenient, let him earn your favor by eating right and behaving properly, YOU are the parent, YOU are in charge, NOT him. Children WANT to be taught the right way to live and will respect a parent who carries out their duties of showing them PROPER attention (with fair discipline when it's called for) and shows them how to live properly. Don't talk to him like an adult (pre-school age?), he wants to be treated like the age he is (he needs to know that you understand he is a child).
Don't TRY to be a parent,...BE a parent. Did you ever have a pet?...did you TRY to be a pet owner or...WERE you a pet owner? Having a kid around the house is not completely different, they both need care and food and make a mess.
Stop giving the kid as much attention as you can, let him see that you have a life too and that you are not a toy (he'll learn to respect you).
Never bug your boyfriend IN FRONT OF THE CHILD to do something that will benefit the kid, the kid sees and hears that YOU can be used for this and will continue to use you. Stop doing what the child WANTS you to do, YOU should be in control (not the child). Once the child knows that, the child will feel safe (the child understands he can't fend for himself).
Don't cry (don't be sad for him) for the boy, let him learn to do his own crying ("mommy, I want to do it myself" is a famous child saying) and let him be responsible for his achievements when he wants something (he sees you conveniently "FEEL" for him and will USE you).
Let him learn to drink vegetable juices mixed with apple juice (veg, juices are extremely healthy (especially fresh) and apple juice makes the taste better PLUS has healthy fiber to work the digestive system). Once the digestive system starts working, appetite for real food builds. Then he will want sandwiches, etc. Also honey is similar to candy. He can learn to like carrot juice because it is creamy (secretly, adults may not think so, but tell him it is). Mix a little garlic in food and drinks (good for digestion and causes "appetite feeling" too).
Let him "GROW UP" (he wants to).