They all sound like MG. Im 20 and was just diagnosed with it. My symptoms got extremely worse right as i was going through having the flu and right after. So bad that i couldn't even lift my legs to get out of the shower, so i had to stay in there until i could get enough strength to lift my legs up with my arms to get over the tub. And with your arm problems-- i had the exact same problems, i couldn't even comb my hair without my arms giving out on me or driving i had to prop my arms on the wheel and took effort to turn the wheel. I went to get blood tests done for MG and they came back positive. I also had "double" vision but i don't know either if it was considered double vision or just trouble focusing my eyes on items. Anyways, i would agree with the other posts and seek medical attention! good luck!

-- Cait