So first and formost when in doubt see a vet. Budgies hide any signs of sickness or issues they may have like professional spies. You can even call the vet explains whats happening and see what they say.
That aside since I can not see or hear your bird all I can say is this. Budgies always do a little tail wag it can mean a great deal many things from excitment to upset. Budgies also make tons of different chirps, squaks, chatters and all kinds of noise. So Id have to hear it to be sure. But call a vet.