2 young children being sick and bile?

ive just been woken to the sound of my eldesdt, 5 and my youngest, 1, thowing up. my 1 yr old is just throwin up her milk and isnt something im feelin overly concerned about. however my son has thrown up all his food (well that that hasnt been digested already) and continued to be sick, he then had a gl of water as he kept saying he was very thirsty and instantly threw it all back and more, more so that towards the end his sick wasnt clear but was yellowy green, i imagine bile. is this somethin i need to seek immidiate medical help with as some site suggest or is this something i can leave him to continue to sleep until morning and go to the doctors if its no better. they have all (i have 3 children) had diorhea for a couple of days now my sick 2 still do have it, my youngest isnt dehydraated but my eldests lips are v dry hes v pale and keeps complaining hes thirsty, however his tongue is still wet and it is the middle night for him so he bound to b thirsty with dry lips. any advice appreciated as not sure what to do n cant remember what my parent did when i threw up bile as a kid