Woke up to sudden pain along the right side of my big toe nail on my left foot. my left toe doesn't look any different than my right toe?

Ingrown: Could be the start of an ingrown toenail but may not appear any different from your other big toe because its not infected at this time.

More than a feeling.: If you really think about it, technically, all nails are ingrown. It is just that some are symptomatic and can develop into problems that might have to be addressed. It might be that when you were sleeping, abnormal pressure was applied to the toe area that has now caused enough symptoms to make your nail feel ingrown. Give it a few days and see if the issue clears up before seeking help.