The only thing I do on rest days for my penis is drink lots of water, so I urinate more and keep some natural quick heat going through it. Do a search on this site for lotions or creams you will find many, like; bio-oil, vitamin e oil, cocoa butter, Nivea, anything with aloe and vitamin e, etc...
And like MrB8 said don't think about Pe until your next workout day. Are you getting lots of sleep too it really helps your body regenerate and rejuvenate. Good luck, be patient and persistent.