My chest,throat, and legs ache after the stomach flu (it mainly consisted of me dry heaving stomach acid) is this normal and what can i do for relief?

Viral infection?: Sounds about right for an acute viral illness. If it does not begin to improve quickly, becomes worse or you develop new symptoms it may then be time to seek medical assistance. Hope it clears up soon.

Vomiting & K+: The retching of acid can cause the lining of your esophagus which goes through your chest and the back of your throat to be sore, try choraseptic and bland foods for a while and both should get better. You can sometimes vomit until you lose potassium and magnesium. As soon as you can eat bannanas which can replenish both. I hope this helps!