I think this is slightly elevated, the pulse in this age group should be in the 120s at rest. But, he has a fever and possibly hypovolemia so this is the most likely reason why he is more tachycardic than usual. He also may need medical care in the form of antibiotics, and/ or volume repletion. I would definitely let you doctor know about the condition of your son.
I also want to add, that he has a terrible stomach, and is quaking a bit. Please let me know if this is normal or if i should be concerned.