can amoxicillin cause a 2 week late/ missed menstrual period? i haven't had a period since july 3rd. i always come on between the 22nd and 23rd of each month. i figured since i started taking amoxicillin and aint on bc that i would give it a couple days. 2 weeks have passed and i am finding myself looking for my period all day long.... could i be pregnant? can amox. have that affect without the aid of bc?