I Have Been Sexually Active With A Particular Woman For

I have been sexually active with a particular woman for over a year. Prior to meeting her I was tested for any STDs, due to the fact that I was sexually active. I tested negative for everything and she is negative as well. Recently I masturbated using a shampoo as a lubricant and within a few days developed 5 small bumps on the rim of my penis that looked liked really small pimples. After showering the bumps were gone and appeared to be scabing over. They don't hurt, itch, nothing. Is it possible to be having a reaction from the shampoo?