It is great that differences have been spotted in your son's nipple. This could be due to moments of redness and inversions whenever irritations or infections set in. It is quite necessary to stick around. If the condition persists or grows more severe, the best alternative would be to seek further evaluation and advice from a pediatrician.

This means that the child could have low muscle tone i.e. hypotonia which could be an indication of brain damage. Other examples include delays in learning new tactics and staying strong like rolling and crawling. It's crucial to get a pediatrician's advice to get the optimal treatment

It can be a sign of constipation or a stomach bug. They might complain of discomfort and pass out if they have constipation. Ensure your baby is taking in enough fluids. If the issue persists, then you must contact your pediatrician doctor for proper diagnosis and treatment.

As a 15 year old boy experiencing headache, fever, body pain, weight loss, and occasional vomiting sensation, it's important to get checked by a doctor. These symptoms could be due to an infection or other health issues. Please visit a general physician for a proper diagnosis and treatment.

At two months old, babies should be fed only breastmilk or formula. Cow milk can be too much for their stomachs, resulting in problems such as stomach pains and anaemia. It is important to consult with the pediatrician before making any changes. 

The signs of a stomach bug can start with vomiting. Stomach pain and headache are also two other possible symptoms. Often, these bugs are self-limiting and go by themselves, for the time being, ensure he drinks as much as possible to avoid dehydration, and feed him suitable light foods. Should he not feel any better in several days, it's the best option to see a gastroenterologist.