Mmm, though proper cycling shorts are a "good thing" and I now wear them even for commuting, I managed for my first 30 odd years cycling just wearing normal trousers, including a few (not many admittedly) trips longer than you mention. So, unless you've literally got your knickers-in-a-twist as it were I'd be looking at a better (ie more appropriate for you personally) saddle. before worrying about shorts or lotions and potions. 50 miles, though very respectable, isn't a ridiculous distance, so shouldn't really cause trouble.
For me, brooks saddle, but I'm a chap, and anyway, everyone's arse is a different shape, but saddle's what I'd look at first - and including right height, fore / aft , and tilt (either dead level or very slightly down at front).
Pretty much everybody here, brooksian or otherwise, will say soft saddles and /or gel saddles are "a very bad thing".
Your story does remind me of a friend who'd cycled across Ireland in two 70 mile days on something akin to a pub bike. To give some context she was half-german rather Wagnerian build and wouldn't have looked out of place in a Viking helmet carrying a spear singing along to Ride of the Valkyries. She burst into the quiet west-coast bar, and as all eyes turned to this apparition at the door, announced extremely loudly to the whole bar "Christ my fanny is f**ing sore !". It was certainly very quiet indeed for a minute or two afterwards.