E-stim went a bit wrong

Yesterday I had the good idea to use my conducting clothespins with e-stim but not by touching the wand to the conducting part of it as I usually did, this time I thought about touching it directly to the sticking out part of the nipple, which would then lead the electricity to the clothespins and everywhere and maximize sensation.

I think this has been the most painful I've got from it, even at the lowest level (pretty much unnoticeable under normal circumstances), even using the tip that hurts the least (the e-stim pen comes with many tips that you can change, well this one is supposed to be the least painful one), even then, I couldn't stand it for too long, now maybe this also has to do with not doing it for a while thus getting more sensitive or the fact that I have my period, but honestly I expected it to hurt twice as much as it combines both most painful ways to use it : touching at the tip of the nipples and the conducting clothespins.

Now usually once I stop all stimulation with this tool the pain is pretty much gone, but this time was different, I don't exactly know what happened. For a few minutes after I stopped, I couldn't tell if I had pain in my heart (but I had a strong sense that it was indeed in my heart), if it was in my chest muscles, and my mind was rationalizing that it could be some kind of panic attack, as I do have anxiety and get these moments where I don't know if it's my heart or if it's just anxiety at times, but never at this intensity.

My... chest/heart, I don't know, was hurting, and I started having a bit of nausea, probably from the thought that it could be my heart and nothing else, but honestly I wasn't even that panicky. I wanted to turn to someone in the moment, anyone, but I was alone in this so I just waited til it passed and went to sleep with my nipples a bit achy.