I have been having a lot of pain in my abdomen on the right side under my breast that goes to the bottom of my belly. It isn't bad if I stay sitting or hunched over but when I stand up straight or stretch out while laying down it is unbearable pain. I don't have a fever and my blood pressure is normal. Any ideas of what this could be? Should I go to hospital?

Maybe not a hospital but you should see a doctor quickly. It sounds like a muscle issue, but it could be anything. If you have a urgent care or something nearby, that might be an option too. Don't let this go untreated for too long.