Deep Heat while breastfeeding

I strained my lower back really bad from moving furniture around and applied deep heat to the area. Wish I had googled it before but only found out afterwards that you shouldn’t use deep heat while breastfeeding as it can get into your bloodstream/affect your milk. I’m scared to breastfeed now lol. I jumped in the shower as soon as I found out and washed it off but I can still feel the affects of it so I think it’s already passed through. :( has anyone else done this? How long should I wait until I breastfeed again? Thank you