Bloodshot eye with blister?

Trauma: A bloodshot eye can occur from trauma or by chance. If the blister is blood-filled and/or next to the most red part of the eye, there was likely a microscopic blood vessel that was temporarily torn, either from rubbing or hitting the eye, or even a short period of elevated pressure in the blood vessel. If this was the case, it will heal over 1-2 weeks. An eye doctor can treat the blister if needed.

Blister: Sounds like subconjunctival hemorrhage with area of clearing or fluid filled epithelial inclusion cyst.

Blister on redeye: If you have a subconjunctival hemorrhage which brightly colors over the white of the eye, the blood cannot seep under the pinguecular area at 3 and 9 o'clock next to the cornea. This becomes highlighted and looks in the mirror like a blister, but it in fact is not. Do not worry about it.