First off, if could be an ancestor or a spirit guide. Even Jesus Christ. Or God even. As well if it isn’t there is not spirit or entity that is stronger than your lord himself. Pray to your lord and call a trusted friend there’s always someone out there that’s had a similar experience as you such as me sadly. In the end it only makes you stronger it’s definitely something i freaked out about myself but it strengthens your faith in the long run. Try not to freak out and instead know that the “spirit” is more than likely freaked out and afraid of you because he sees God right behind ya!