What Is The Delayed Periods,cramping And Vomiting?

i m trying to conceive...i got my first iui done on 8th of april..i m taking naturogest 200 ...the doctor asked me to take a test i
on 23rd of april...which shows faint positive in urine test and negative in blood test...but i m vomitting and having cramps but no period...can it be late implantation..? can i be pregnant ? should i continue my tablet or stop them ?