I recently finished doing some home improvemtent work in my kitchen, new counterops, 4 inch backsplashes, new sink and plumbing, new dishwasher and a fresh coat of paint. Starting 2 days ago I noticed a strange smell in my kitchen and also in the upstairs hallway. I can not identify the smell as its not a musty, moldy mildewy smell or the smell of a rotting dead animal or anything like that. From my own investigations I can find no leaks or drips anywhere in the kitchen around areas I have recently completed my work. The house is pretty old, build in 1929 and I have only lived there 8 months so I am wondering just how concerned I should be about this mystery smell. We recently had 4 days of 80+ degree weather with relatively high humidity as well but I didn't notice this smell last summer when I first moved in. Any advice or ideas about what this smell is would be greatly appreciated.

Lots of plumbing and hot temps, bad smell and no leaks. This is not going to be easy. Did you do any changes to your vent stack?

No I did not touch the stack at all. Although yesterday after returning from work the smell was almost completely gone, either that or my nose has adjusted to it. Just some more background info I have also recently moved some electrical outlets in the kitchen 3 to be specific. I had to move them in order for my new 4 in backsplashes to fit. Not sure if that can play into it somehow. Also I used a TON of liquid nail to attach the backsplashes to my walls. The house is 90 years old and the walls aren't exactly smooth, especially because they are fake brick. I also used some standard crystal clear caulk to make sure the backsplash is safe from water but that stuff essentially smelled like super glue. I am wondering if it could have been sewage coming back up through the pipes? But it didn't smell anywhere besides the kitchen. I am totally perplexed any thoughts?

Adhesives like liquid nails can give off fumes for weeks and if your heat turns on the smell can get extra funy. Hope its gone completely in a few more days or come back and tell us what's happening.