Child With Pain In The Stomach, Sore Neck, Smelly Urine, Vomiting And Diarrhea. Need Treatment?

Hi there, two weeks ago my son got a fever and ended up with a sore tummy and vomited and had diarrhoea for a few days. Then spent a week fine. Then for last week he has had the fever on and off all week, eating has stopped pretty much all of today, and had a friends birthday party today and spent most of the time having sat on his nanna s knee and ate maybe one piece of food. Tonight I noticed he was sweaty once again and he had fallen asleep in seconds after being awake not long before and I had to wake him to take panadol so he could go back to sleep. I don t have a thermometer but I know his temp has been high. He s had no vomiting this week, his urine has started to smell today, and for a normally very active kid he is now doing nothing. He did say today the back if his neck was sore but other than that hasn t complained of anything. Any answers would be great. Thanks Antoinette.