Incipient Infestation - bugs seem aggressive

I have dealt with bed bugs infestations. I am living with a friend temporarily. It was all fine until a few days ago. My friend is out of town for a few weeks, left about 10 days ago. For the past 5 days, I've noticed bites on my legs and hands. Contrary to popular (internet) info, I CAN feel the bugs. I've seen the bites bleeding or yet to fully coagulate. It may be because they are young and use less saliva. Mostly had bites when wearing clothes, outside the home. It's cold so there are multiple layers of clothes. Have been bitten on legs, feet, arms, shoulders, ears, face, eyelids, scalp. I can't imagine how the bugs got here, or how to fix this quickly. I am somewhat confident I didn't cause this, but I feel responsible.

Location: Toronto Midtown rental apartment.

Cimexa, crossfire, bedlam, or anything useful are basically unavailable in Canada. Exterminators are very costly.

I have some questions.

1. How are they getting on me when I even strip off clothes and not standing on a rug or bed etc. They bite me on the shoulder, for e.g. How do they get up there so quick? Bite was still bleeding(didn't touch or scratch) so very fresh.
2. Why don't I ever see the bugs. I know they are small. They are not invisible, and I am not crazy, there are bites there. I know the feel of a bed bugs rash, and these bites and rashes are the real deal. Am I losing my mind?
3. There is a sofa chair which seems pretty infested. I get bites when close to it. Even standing 3 feet from it. This place has carpeting, much of it shaggy. Afraid if I spray on one spot the bugs will relocate. I can't call the landlord, it's not place but afraid my friend will blame me. It must have been in the making for a long time, or is that wrong? How do I address this troublesome sofa? Can I protect the bed by placing the "feet" in Cimexa-dusted bottle tops (plastic peanut butter jar caps)? One bedroom apartment with furniture.