Worried about this pain?

The right side of my stomach gets this sharp/dull pain sometimes and my stomach makes noises like I'm hungry and some times gets weird fluttering sensation and I feel sick sometimes and when I wanna burp or something sick might come up or thats what it feels like will happen... i had blood tests about 3 weeks ago and i'm due on in a week and there is 1000% chance I'm not pregnant... could it be trapped gass or constipation? Only recently finished my iron tablet course about a week or so ago and O do sometimes suffer with constipation.... any idea what it is? Thank you xx