Teenager. Confused, Sluggish, Severe Pain In The Head, Diarrhea, Body Ache. History Of Being Hit On Head During A Match And Was Out Cold For Few Seconds. Serious?

My 15 year old son took a blow to the head yesterday at 2pm ish during a national rugby tournament and was out cold for a few seconds. He came round and seemed ok ... ?? ( to them but not to me!!)The coaches put him back on to play in the next game. He is a determined boy who wanted to play but to me looked confused and sluggish. Came home ( London to Wells)and he said his head hurt a bit. This morning he got up and despite my advice went for a cycle ride but had to be collected as he felt to ill. ( i tried to tell him not to go but he thought fresh air would help! I said no!!) He now has diarrea feels sick but has not been sick... says his whole body hurts and his head is very bad 9/10 pain... advice please... hospital,111,999 or keep an eye on him throughout the night?