Hi. Thanks for your query. Noted the history about your baby who is 6 weeks old and is on formula milk- takes about 4 ounce every 2-3 hours, you try to make the baby burp but he will spit up sometimes, always gets hiccoughs, constantly crying and being fidgety after feeding. I would advise you the following: Take the child to a Pediatric Surgeon for clinical evaluation to have palpation of the abdomen for a classical unripe fruit feeling on the right upper side of a Hypertrophic Pyloric Stenosis and go for water soluble contrast study for the same. If positive, the baby needs a surgery to release. If this is not present, the cause is medical like intolerance to the formula milk and may need change and you should take help of your Pediatrician for this.