Sometimes your landlord will cover an exterminator if, say, your neighbor has an infestation of fleas or bedbugs that jumped over to your apartment. I once fostered a cat that had too many fleas. My landlord actually paid for the extermination. The fleas died, and I had a ton of cleanup, but I felt better a week later. The kitty went to a better home with a flea bath. The kitty lived a long and good life with a family.

I also had to deal with bedbugs in a different state that was infested with them. It was horrible. Their bites are like two or three together, and sometimes all over one arm or back or leg or multiple places. Usually they bite in twos or threes, and you'll see like small red welts. If they are super itchy, it's most likely bed bugs. Those are harder to get rid of.

They can enter your home if you purchase used furniture, travel anywhere, help someone move, deal with a neighbor who has an infestation, purchase items without knowing they had bed bug eggs (like at Target, when they resell returns that look new, but aren't), etc.

A specialized exterminator would need to come out and figure out where the infestation was. For me, it was a few bugs in the couch, where my friend slept on and brought to my home. I wrapped the couch in plastic and paid for a special removal - with notifying them that it needed to be fumigated. My friend also broke my couch's arm, since she was obese and didn't know her weight. I paid for that myself though. I knew she was embarrassed. But I never had any friends spend the night after that. This was about 8 years ago, give or take. The bed bug problem went away, but I didn't have an infestation. It was just a couple of bugs she brought over from an infestation at our college. Horrible times!

I hope you find the source.

You can also see if you have poison ivy or something like that, too, which is more manageable than a bug infestation.