are the symptoms allways the same with crohn's?

My son is 15. 9 weeks ago, he became very unwell whilst climbing a mountian, and had to 'go' there and then. A bout of loose bowels and stomach cramps lasting 3 weeks followed, then it clamed down for a day or 3, then returned with headaches and fatigue, we where given 2 types antibiotics, the loose stools then calmed a bit, but the pain became worse. he has since had sore throats,occasional inability to keep breakfast down, stomach pains (lower right on the whole), headaches, and nasea, these have become our lives,there is some respite for a day or two, but never for long! he has missed school almost constantly, as when he went, they had to send him home. He now has what the doctor termed a severe ear infection, and is on amoxicillin for this.i think this is a result of bieng so run down, he is rather on the thin side, BUT he is now eating fairly normally again. the first bloods taken 5 weeks ago where normal, but he has declined in health since, and struggles to walk up the lane without discomfort. However, his bowels are now back to normal, just pain, nausea, belching and burning when he does pass a stool. We see the GI on friday..they have mentioned colitis, appendicitus, crohn's and IBS..i had anal fistulas and abcesses as a child,and had surgery twice for these. and there is coeliac in my family, for which they took bloods that are not back yet (5 weeks ago), my brother had a sort of bowel stretch thing done too, but i dont know what is relevant, i just know i want my son to get his life back. any advice or help appreciated. thanks.