I think a blog could be an excellent idea. If you're worried about coming off whiny or "boo-hoping", it really depends on how you present it. There are plenty of blogs from people without major issues, or even what the half of us would think of as a minor issue who come off whiny enough... "Like omg I totally ran out of tampon and had to use a pad and with my brand new Gucci jean too


" yeah somehow not thinking that's how you'll come off. But there are just so many blogs like that which might be why your friend advised against it.
I do understand the frustration though, and even my husband who goes to the doctor with me, has done research and is in general an understanding soul, still questions at times why I can do X today but not again for weeks, or if I do Y, I can't do B, but A and C are still okay. And still seems to think that if I just "take it easy" I'll be fine and my bad days are brought on entirely by my overdoing things.
You can educate till you're blue in the face, even some (at times many!) doctors and nurses have issues understanding, so it's not really the ignorance of the masses, it really is just the nature of the disease itself.
So when friends question me, not that I have a bunch thanks to this combined with general anti-social preference, I use humor mostly to deal with it. They get told once the generic definition of MS, neurological disorder that affects the central nervous system and are free to google it.... From there the humor/sarcasm switch gets flipped to the on position and duct taped.
Excuses for not hanging out the night before.... "My immune system ate all traces of your existence from my brain last night, but thankfully regurgitated it this morning." ... Using a cane today but not yesterday... "I'm in training for a three-legged race." Forced into crutches and braces for a time... "Let me tell you, never borrow some eggs from the Easter Bunny, when he says he'll collect with interest....." In a wheelchair... "Well Y'know when dead turtles are screaming past you hollering 'slower traffic keep right!'"..... Popping pills at lunch... "Skittles! Always gotta have dessert before a meal" Undergarments "Omg! You haven't heard the bustle was back in fashion, these here are great for giving the "Rembrandt" curves (eyebrow wiggle/ sexy pose) and sooo much cheaper than the ones from Victoria's. I always carry a spare since who knows what could happen with a body like this"

well you get the idea.