Is my thermometer broken?
I think it's fairly common to have several "flat" temps in a row -- but it is a funny feeling when it happens! Unless you feel like your temp readings changed dramatically following the water, I wouldn't worry about it. It seems like water would either short it out or nothing (maybe?).
I think you're pretty normal having strange cycles coming off an IUD, also, and there are a lot of ladies on here who have gone through it -- if you need help interpreting your chart, the Charting to Avoid (Or Whatevering depending on what you're doing) is a relaly good resource.
I had the same issue with a Walgreens thermometer, minus the water spilling. I switched to a BD one that got good reviews on Amazon. I'd be able to tell you if that seemed to fix the problem, except I got pregnant the month I started using it!
I tried switching the battery on the Walgreens and it didn't make a difference. 97.18 was one of the temps I always got too. It still showed a shift with ovulation, but I didn't trust it. There were like four or five temps it gave me over and over.