A bat bumped into me from behind on my neck. its been 7 years now, i dont know if it bite me or not. can i get rabies now due to that encounter?

Doubtful that : you will get an active infection from a bite after 7 years. Whatever ails you, it's not likely from a bat bite. However, if you had a tick bite, you may have some tick-borne diseases like Lyme disease or ehrlichiosis that can manifest itself much later on in life. See a healthcare provider to rule out such conditions if you have symptoms.