Hello,the type of bump which you are mentioning it looks like that you have an ulcer on the back of your tongue but you have not mentioned about the history i mean that since how long you are seeing this ulcer, did you got any cut from your teeth in that area or do you have any habit of smoking
or taking tobacco. If there is nothing like that it can be an aphthous ulcer which will heal within 1 week you just apply a topical ointment named mucopain, but if there is a positive history of trauma you need to get the tooth which is causing trauma removed. in this case you need to visit a dentist
nearby, get the treatment done and report to me back.