I take a dexilant (dexlansoprazole) in the evening for my heartburn and ulcer from crohns flare. Can I take an omeprazole in morning if it starts to bother me?

No. Dexilant (dexlansoprazole) effectively blocks acid secretion over a 24 hour period, and you are not likely to get any further relief by adding omeprazole. Indeed, if it's your Crohn's disease that is causing your pain, a different therapy may be indicated. Consult your Gastroenterologist.