I get random tingling/crawling/goosebump feelings on my back under my right shoulder blade. it happens at random. what could it be?

This is very likely: a temporary nerve compression or dysfunction. The tingling nature of your symptom suggests nerve involvement. Something might be pressing on a nerve near your shoulder blade (could it more likely happen when you are lying on your back/shoulder blade?) The reassuring thing is it sounds transient and resolves quickly. Unless it worsens in frequency or intensity, or spreads in location, OK to watch.