Upper ab and middle back pain

zombie_meg

I started doing 30 day shred a few days ago. I did two days, took a rest day, did day 3 today. A few hours after my workout I began to feel upper abdominal and middle back pain. I feel nauseous and no positions have helped. A heating pad helped my back but my stomach is still hurting. Any ideas of what this pain could be? It's been constant for about 5 hours.