I am not the doctor.
If you have protected sex you cannot get pregnant. That is why you protect yourself, right?
Only when something goes wrong with the condom do you have to take I-pill. It is your responsibility to look at the condome when he takes it off to make sure it did not break. You can also figure out from what is flowing out of your vagina after sex if the condom broke. If the condom broke, you will be very wet and his semen will flow back out as a very watery flow.
I-pill is a VERY strong birth control pill. It is not without side effects, which is likely what you are getting now. You may also get a period around May 20 when the hormones leave your body. It is also likely that your next cycle and menstruation will be disturbed.
Take care!