Could I be pregnant

I just went and visited my boyfriend after 2 months because he's in boot camp, Anyways we had sex only once but was on the one day this app said I had a high chance for pregnancy. I started having cramps, my boobs hurt like they're having cramps, very bad headaches, going to sleep super early, diarrhea, not really wanting to eat then becoming super hungry. It's only been 4 days since. Also a clear milky color discharge.