If he hasn't been eating it could be low blood sugar which you can give him some light karo syrup to bring his blood sugar back up. When Tyke was small he done this sometimes. His vomit would be yellow and he would just lay around but this was when he wouldn't eat for long periods of time.
I gave him 1cc with a syringe and in about 45 min. he's was ok. Then you usually can get them to eat. hope this may help if it's pertaining to his eating.
__________________ I L ve My Sweet Tyke 
I can do all things through Christ who stengthens me. Phil.4:13 |