I feel i have to go but blocked up.my stomach hurts haven't gone in 3 days?

Try an enema, then: That is just a tiny bit of backing-up. At this point, i would try to evaccuate by using a fleet enema, (sodium bisphosphate) follow by using a gentle laxative such as senokot-s or even the miralax-powder, both are otc. Increase fluid, roughage such as fresh leafy veggies/fruits, regular use of fibers and increase fluid intake, and keeping physically active. If this persists, consult doc. Good luck.