http://www.kellymom.com/nutrition/solids/solids-when.htmlSigns that indicate baby is developmentally ready for solids include:
Baby can sit up well without support.
Baby has lost the tongue-thrust reflex and does not automatically push solids out of his mouth with his tongue.
Baby is ready and willing to chew.
Baby is developing a “pincer” grasp, where he picks up food or other objects between thumb and forefinger. Using the fingers and scraping the food into the palm of the hand (palmar grasp) does not substitute for pincer grasp development.
Baby is eager to participate in mealtime and may try to grab food and put it in his mouth.
The American Academy of Pediatrics and the World Health Organization recommend that babies be exclusively breastfed (no cereal, juice or other foods) for the first 6 months of life. There's nothing that I've read that formula means it's ok to start solids earlier. I have more links if anyone is interested. Giving solids won't help him sleep either. That's a myth.
Ethan is what? 4 months? He could just be growing and not truly ready for solids. Just something to think about.