Yuck! I am so sorry!!!
I don't mean to scare you, but a friend of mine had something similar happen recently. She started noticing those giant black flies (horse flies?) in her condo, and it got to the point where she was killing 20+ a day... she was pretty convinced eggs had been laid in a wall somewhere or something. She didn't do anything about it (fumigate, exterminator, etc) and the problem eventually resolved itself. But if I were you, I'd feel more comfortable calling an exterminator and describing the problem instead of waiting it out. They may be able to give you advice, or be able to ID the bug, or tell you that they need to come and do some work in your house... doesn't hurt to call!