I'm getting really bad pains

hello ladies I'm getting really bad pains on my stomach. I will be 12 weeks tomorrow and I drank the medicine they gave me for an std and now I'm hurting bad. it feels like contractions but also like if I had to go do number 2 but I go and nothing it comes and goes really bad. what should I do ? should I go in the e.r? And I know what contractions feel like because I already have a 6 year old daughter