Pimple On lower shaft of penis

I am 16 and have had a GF for about a year and we've been having steady sex for about 9/12 months. we both are each others firsts. recently after getting it on today i had a large pimple looking thing on the mid to lower part of my shaft. we both got freaked out and i told her there was a pimple there before and we looked it up and found pictures that look exactly like this and it said it was an ingrown hair. I really hope it goes away and thats all it is. anybody else have this and is there anyway to get rid of it besides waiting?....Oh. i have also switched up my showering schedule and have been working out and i shaved down there bout a week or two ago. im thinking those could be major factors. I Dont Know though. Please if anyone has something like this respond asap.