Fieldstone foundation - source of water?

I have a roughly ~100 y/o house in Massachusetts with a fieldstone foundation. The basement was "finished" when I bought the house (drywall, sheetrock, no insulation) and I simply left it alone. A recent project has led me to remove all of the existing drywall so that it can be properly finished. The rest of the basement has no noticeable water or smell of moisture, but upon pulling off the drywall in one corner of the house, I found a strong water smell and moisture behind the wall.

In talking to a contractor, he told me he thinks the water was from a washing machine pipe (there was a p-trap attached but it is cracked, pictured) that had cracked at the joint and was likely leaking the whole time. My only concern is the opposite wall appears to potentially have had moisture, but then again, I also don't really know what to look for, because maybe it's the window (right at grade)?

Link to photos: (apparently I need one post but this should count as one post): imgur.com/a/BVA51NQ

Trying to figure out if I should be calling a mason/trying to fix my grading outside, or what the next best step is? I have a dehumidifier and air mover running to get it dried out and it appears to be working.

Thanks!