Can i get ear piercing while having toothache?

It is best you have the toothache treated first

I guess you could, but wouldn't it be wiser to focus your attention and time on something you need to do (fix your tooth) rather than something you want to do (pierce your ears). Ears can wait, toothache cannot. There may be an infection that requires immediate attention.

Most common cause of toothache is infection. Not wise to do any surgical procedure (including piercings) in the presence of active infection. From cosmetic standpoint the 1st thing people see when they look at you is your mouth, not your ears. Please, resolve any and all infections before considering other options.