I Have Just Finished Being On The Pill For A

I have just finished being on the pill for a month so I am having sex with my boyfriend without a condom, but even before this, I have had to go for a pee frequently and I always feel hungry but when I eat I feel full really quickly and I feel weird pains in my belly and I'm feel tired all the time and I have back pains that aren't too bad, and I also feel sick but I dont be sick, what can this be?