It may be that when you removed the wall paper , the top of the dry wall came off with it. You may have to coat it with a type of sealer before you cover it again. Ask at a paint or wall paper store.
Paint over it and don`t worry. I just go thru painting over my kitchen and dining room with the brown paper beneath.I just gave up on the scrapping and all the chemicals to remove it. Looks great and no problems yet, Good Luck.