"Oh no, not again..!"

First thing is to check for immediate threats, whilst moving my hands over my body to check if the blood might have been mine (checking for wounds).

If all clear, move on to the environment, check mobile devices for a digital trail: calls made, texts, missed calls, or internet searches made during the missing time, whilst at the same time checking the room for possible entrances and exits, and listening for what lays beyond.

Using the condition of the bloodstains (dryness), last known activity (devices), and body temperature in comparison to the ambient room temperature, try and estimate how long one has been out.

Check any blood on the floor for displacement, as that shows movement against time, and numbers of individuals possibly present at the time, or currently (especially near possible routes of entry). All the time continuing to listen for possible movement outside of the room.

Now I'd be on my knees, quickly observing the knife without touching it, and scanning the environment for an improvised weapon if something legitimate isn't apparent. Crawling to an exit such as a door, I'd scan, and smell under it for any sign that someone could possibly be in any adjoining rooms/spaces. I'd also pick up something to possibly throw, and if the next room seems empty/silent I'd rapidly make my movement into it.

On entering, scan for threats, resources, and then evidence, in that order. If there are threats present, compare to the current state of health, and threat level, in relation to exit routes, if escape is likely to be impeded then engage.

If it's a space I own, gather items suitable for bugging out, and rapidly change, if not, unobtrusively move to see how these rooms tie into any larger structure: corridors, windows, fire-escapes, loft spaces, and stairwells.

If it is an unknown space, take off shirt, use it to rapidly clear obvious signs off the self, then use it to pick up the knife. Apply suitable resources (such as found clothing) whilst planning route away based on apparent information.

Exit strategy. Once clear, stay away from common thoroughfares, all the while looking for a more rapid exfiltration, and replacement clothing/resources of opportunity. Once isolated, begin gathering evidence for the unknown period of time. If suitable, contact authorities.

TL;DR: GTFO