If your oxygen level drops too low, could that cause a non epileptic seizure. also, if you have severe copd would exercise lower your oxygen level.

Yes and yes: A very low oxygen tension can make people have seizure like activity or unconsciousness depending on the response of the cells of circuitry in your brain. The cells can become irritable and have more discharges. People with COPD are exercised to see if they need o2 as oxygenation can drop with activity depending on the severity of disease.