Since you have taken the emergency contraception
soon after, you are amply protected. The burning could be due to the trauma associated and could be due to some amount of urethritis
. It should subside with rest, fluids and antibiotics. The bleeding observed is the withdrawal bleeding consequent to the pill intake. The nausea
is also due to the antibiotic and pill effect. You may also expect your next normal period to be delayed by a week or two and if you do not see it by then, get help from a specialist. Hope this helps.