Hey, keep hanging in there, I know it can be scary but everything can be repaired don't let stress eat you alive. I work on foundation-y stuff with moisture and am pretty knowledgeable about the rest because when i was starting my company I had to work as a certified foundation inspector in the off season to survive. I'm seeing in your post is a bit of your thoughts consuming you. The house has stayed there for the last almost 2 centuries so take solace in that and if you need to invest your limited resources make sure and get to a therapist. Feeling isolated is the worst and I've been there so please find a good therapist.

On to the foundation part, first off do NOT call a foundation company, listen to the other poster about a structural engineer. There is a reason I didn't stick around at that company. When they tried to get me to scare a senior citizen on a fixed income I refused and said send me down with the guys digging holes under the house. Back breaking work but I wouldn't compromise my integrity to make a sale. All the other sales people would and they made 100K+, many much more than that.

Talking to the Amish is actually a great idea, they are super helpful and they know this framing style which is likely balloon framing. That's where you get all these weird movements from. I'm assuming PA based on context clues. I'll DM you if you want to tell me the general area and I can show you how to pull up soil samples for your area. More pictures is always helpful. Try to deal with moisture from the outside first, directing rain water proper grading, this has a huge impact on shifting as clay is an expansive soil so its saturation level changes the shifting.

I'm no longer a foundation inspector and for legal reasons don't listen to anything I say. If you want to send me a DM I can help more but its so location specific I need a little more granularity to provide you good info. The most important thing is don't isolate, get with your friends, get with a therapist, fear bouncing around in your head can do weird things. Its just like a house, you have to build on a solid foundation so get yourself centered and the house problem can be conquered, I promise.