I woke up w blood blisters on the right side of my mouth, what could have caused that and is it ok?

Tongue? or mouth?: Her.Zoster virus can infect and cause lesions more of one side . For eg. Lesions on the tongue -can be from the 7 th cranial nerve -facial n which supplies the anterior 2/3 of tongue sensation , or if related to the gum.Inside of cheeks could be related to 5 th n called trigeminal nerve. Herpetic ginegevostomatitis is another condition in which the herpes simplex virus can cause similar vesicles.

Pemphigus: Blisters in the mouth, inlcuding those that have blood in them and then go away on their own, might be a sign of what's called vesiculobullous eruptions. They are usually of unknown cause, might be autoimmune, and are difficult to diagnose without a biopsy and special staining techniques by a pathologist familiar with oral lesions like these.