I think it is quite comon to have a reaction like this to the flu jab, among others. It can also induce flu like symptoms, I wouldn't be tto concerned unless it gets worse or persists.
Diagnosed HEDS December 1st 2005. DD1 (20) HEDS and scoliosis (now corrected by surgery), diagnosed June 2006. DD2 (18) mild HMS. Son (11) some hypermobile joints, poor muscle strength and seems to be developing scoliosis as well, woopee!