Symptoms began between 12-24 hours after visit to dentist for a fairly serious root canal that lasted four hours. During that time I was given three shots of lidocaine to numb lower jaw because I could still feel the drill. Tremors in right arm and hand occurred during procedure, but I thought it was nerves. Also had unusual back pain during procedure that I blamed on the chair. The rash/itching, nausea and confused taste buds began next day, continue 48 hours later. How long will this last and should I be worried? Thanks for any advice..